2068 A.D. – Captain Black, an highly-regarded senior agent of the world security organisation, Spectrum, makes an uncanny mistake while conducting a research discovery mission on Mars, trying to evaluate where a set of mysterious signals have been originating from. But while doing so, he mistakes a surveillance device for a defence weapon, when discovering a massively-scaled, futuristic complex, built and controlled by an unknown force, who specifically call themselves ""The Mysterons"". Unintentionally destroying the peaceful colony, Black is taken over by the hostile power, and from there on, will be the Mysterons' primary instrument to devise their acts of retaliation, swearing upon their declaration that they will annihilate all life on Earth and will unleash a very extensive war of nerves upon the innocent planet. To make their unveiling statement known, they plan to kill the World President, and in order to accomplish their first attack; the Mysterons cause the car which Captains S

A Mysteron sniper performs an unsuccessful attempt on the forces' new target: The Director General of the United Asian Republic, with Captain Grey arriving in the nick of time, and succeeding in disposing of the eavesdropping gunman. From there on, all personnel from Cloudbase and Spectrum H.Q. – London, along with the recovering Captain Scarlet, and his original partner Captain Blue, are dispatched to protect the Director General at all costs, whom has made arrangements to return to his home country. But the Spectrum officers are completely unaware of the inbound Mysteron-reconstructed civilian Stratojet airliner, the enemies' tool to fix and complete their assassination upon the important international foreign figure.

In the centre of London, the capital of England, a double police-escorted transporter, carrying a nuclear explosive device, built for civilian use, seemingly goes out of control, shaking of its' motor guards and its driver regaining conscience in a back alley. The transporter, now in the remote-controlled possession of the Mysterons, has been hidden in an under construction car park. Captains Scarlet and Blue are assigned to investigate the drivers' mysterious discovery, that the famous Big Ben clock struck 13 times, which may be a clue to finding the transporter, before it destroys the whole of Central London. However, the driver's founding's are more than unreliable due to his perplexed state of memory.

At the Culver Atomic Centre, located in Yorkshire, England, Captain Black accidentally exposes himself to a short-term radioactive isotope, when detected by the security guards, causing his hesitation. Although the isotope is physically harmless, it makes him a straight-forward target when using radiation-tracking systems during Spectrum's full-scale manhunt, to uncover and apprehend the Mysteron agent. But when the organisation is decoyed, Black manages to kidnap Symphony Angel, who disobeys direct orders from Colonel White. Instead of maintaining her aerial surveillance mission, she finds herself on death-row, in a radiation chamber, and Black in absolute control, with the judgment of killing her, or letting her go free.

The Frost Line Outer Defence Base Network, is endangered by the Mysterons when they destroy a maintenance truck, murdering it's engineer/driver in the process, as a cover to infiltrate the defence bases sited in Northern Canada, where the Mysteronised engineer intends to proceed in removing all oxygen from the bases' self-contained atmosphere. With bases' ""Red Deer"" and ""Carriboo"" already taken down, the next base in the ring, ""Big Bear"", is the Mysterons' final target, but if the base is attacked also, the commander-in-chief of the defence network plans to commence a vengeful missile strike on Mars, where the main Mysteron complexes are established. Colonel White desperately wants to prevent this from happening, and so, he assigns Lieutenant Green to his first off-base, ""in-the-field"" assignment, along with Captain Scarlet, to evaluate just how the bases are being cut off, and stop the maintenance engineer from triggering off a global disaster.

When a radio station relay and communications satellite is recreated by the Mysterons and its course altered towards Cloudbase, Colonel White orders the fatal missile to be destroyed before it collides with the aerial base. Infuriated at his superior for dis-regarding the non-existent, but beknown to Scarlet, lives of the men on-board the satellite, he declines White's proposition to be temporary commander-in-chief of Cloudbase, and therefore, the offer is handed to the honoured Captain Blue. Leaving for a surreptitious destination, which only White has exposed to Lieutenant Green, and with harsh instructions not to publish it to anyone at all, he arrives on-board the USS Panther II submarine, with the alias Robert Snow, where shortly after one of the ensign officers is, with intent, murdered and reconstructed by the Mysterons in their newest play of vengeance to kill Colonel White.

A World Air Force plane, carrying Commodore Goddard and his right-hand man, and being escorted by Melody Angel, is struck by a shocking clash of thunder and lightning, and crashes, directly becoming the object to be reconstructed by the Mysterons. The force broadcasts it's current threat, that they aim to kill all 10 of the worlds' top air-chiefs, who make up the executive Supreme Command of the World Air Force, who want to discuss a plan to dissolve the war of nerves between Earth and the hostile force. They plan on doing so, by holding an International Air Conference at the loneliest location in Europe and the UK; Glen Garry Castle, in Scotland, which the Mysteronised Goddard has chosen to hold the conference to be. This is however unknown to Colonel White, who is awaiting the approval from Captain Scarlet, that the castle's security is set up and approved. After she brings the delegates to the castle, to start the conference, Symphony Angel is taken prisoner, as is Captain Scarlet,

General J.F. Tiempo, the Commander of the Western Regional World Defence Government, is submitted to the Mysteron's next punishment target, and the doctor who will perform a major and much-required operation on Tiempo is eradicated during a dramatic car crash involving Captain Black, and reconstructed by the Mysterons. Spectrum are still befuddled on how the force have declared their act of retaliation as to ""kill time"", but Captain Magenta eventually cracks the dilemma and an elaborate game is underway by the Spectrum personnel, in order to trap the person who will take the life of the General, but two advantaging surprises are about to be opened by the Spectrum officers, which will undoubtedly assist them immensely in their contemporary battle with the Mysterons. But, what they don't realise, is that the doctor who will pefrom the neurosurgery operation on the General is a Mysteron killer.

A divulged, top-secret meeting with the World President and two Spectrum Intelligence Agency officers, one of which is a general, the other a science doctor, who has created a new Mysteron electrical gun & detector following the inexplicable events with the late Doctor Magnus who attempted to kill General Tiempo, takes place in the shooting grounds of an African private game reserve. Colonel White and Captains Scarlet and Blue find themselves in a treacherous hunting sport, when the Mysterons helplessly attempt to prevent Spectrum from conducting the usage of their two brand new and innovative mobile weapons where one can kill a Mysteronised person with a strong electricity voltage, the other can distinguish and identify Mysteron characteristics within a person using normal X-Ray systems. But, unbeknown to the group of men, there security officer-in-charge, Captain Indigo, has been murdered in cold-blood by Captain Black.

Spectrum Intelligence impart Captain Scarlet with a ""special assignment"" which is to consciously loose inadequately at a casino, and to place himself on their debt owners list for 5,000 credits. When this is reported to Spectrum Headquarters, Colonel White fires Scarlet on the spot, for improper use of the organisations' code of conduct, and his occupation taken away from him. Living in a inexpensive, shabby hotel room temporarily, a pair of Mysteron agents, posing as sought after gangsters, formulate a deal with the now Paul Metcalfe, with his I.O.U. for 5,000 credits, in return for a Spectrum Pursuit Vehicle, which will be utilized to brake into the Nevada Nuclear City Complex, with an atomic incendiary device, which will obliterate the whole of North America.

A professional vault break-in duo seek out a minor Spectrum Security Vault, near the coast of New York, where ""useless"" documentation is taken, which proves quite valuable to the lawbreakers. Along with another gang member, they simulate a fake play-act for a forest lookout warden, just on the outskirts of tthe American capital, as hopeless, potentially dangerous drunks. They set-up their car with fake look alike puppets to deceive the warden into thinking that the 3 drunken men that he just warned, has helplessy crashed off the high mountaineous road, and exploded into a fireball. The gang then take care of the warden and, deliberately posing as Mysteronised humans, they announce the force's latest peril to destroy the Second National Bank of New York, however the real Mysterons have yet to announce this at all, except for stating that they will destroy ""The Heart of New York"", but Colonel White understands that the bank is more than vital to full-fill the threat, as it stocks the en

The commanding controller of Lunarville 7, a small colonised base on the opposite side of where the main Mysteron complex is located on Mars, announces that he has made direct contact with the force, and agreed to a undisturbed, and peaceful settlement, and to finally end the war of nerves, but this is a trick by the Mysterons, as the controller and his personnel aid are reconstructed agents, and have Captain Scarlet, Captain Blue and Lieutenant Green trapped on the compound when they are sent to investigate how he managed to make a deal with the Mysterons. When suspecting that the controller and his right-hand man could be Mysteron agents, they non-attentively leave Lunarville 7, and travel to the Humboldt Sea, the far side of the Moon, where an enormous, and potentially powerful Mysteron complex is being developed and built in Crater Number 101.

A modern generation kind of tank, the Unitron – a deadly computer-assisted vehicle, is seized by the Mysterons to destroy the Supreme Commander of the Earth Forces, when he is escorted by Captain Blue to the tanks' testing range field in the Sahara desert. Two of the Commander's highest-ranking officers, Colonel Storm and Major Brooks, while en route to the SHEF headquarters, are killed in an explosive collision in a mountain-integrated tunnel, involving their car and a gasoline tanker truck, and consequently revived back to life with Mysteronised bodies. Both men are used as composers to complete the Mysteron's threat, with Major Brooks' attempt becoming unsuccessful, but Colonel Storm's turning into a life-threatening situation when accompanying the Supreme Commander to Point 783, the acting command post where the two test co-ordinators are carrying out final tests with the Unitron, but little do they know that the Mysterons have programmed the mighty formidable weapon to seek and de

Two models, eager to make their names publicised and internationally-known in France, are killed in a dramatic staged monorail-train crash, while en route to the countries' capital Paris, and are rebuilt by the Mysterons, in a bid to assassinate Andre Verdain, owner of the ""House of Verdain"", a top modelling & fashion design company, which keeps his real occupation as the controller of the European Area Intelligence Service a confidential secret. Captains Scarlet and Blue, along with angels Symphony and Destiny are assigned to act as French newspaper photographers and stunning, attractive models, in order to guard Verdain from any Mysteron attacks, but they are absolutely oblivious of the presence of the two female model doppelgangers.

The Mysterons present to Spectrum their new act of avenge; to kill one of the Angel pilots, and with Destiny on vacation, she is their apparent target, so Captains Scarlet and Blue fly to Paris to pick her up and accompany her back to Cloudbase. On the way back, 3 brand new, un-painted Angel Interceptors, reconstructed from those that were subsequently destroyed in a scorching warehouse fire, open fire upon the Spectrum personnel, but a daring dynamic and enthralling aerial dogfight between the Mysteron aircraft and the real Spectrum Angels ensures, testing Melody's Rhapsody's and Harmony's outstanding skills and training to the maximum.

A Variable Geometry Rocket is hi-jacked by a Space Major Reeves, an old accomplice of Colonel White's, who launches the space-plane and makes a quick departure in a fighter jet with the rocket's flight programme unit, which only he knows the 4-letter self-destruct code, to obliterate the rocket before it knocks out an essential target, which happens to be Base Concord, the state-of-the-art airbase where the rocket originally left from. Captains Scarlet and Blue are assigned to self-destruct the rocket, before it reaches Base Concord, but to accomplish this, they have to check 10,000 possible 4-lettered code-words, starting from 'ABLE', and they don't even know that Reeves has set the destruct code-word as 'ZERO'.

This episode concludes from where Captain Scarlet, Captain Blue and Lieutenant Green left the remains of the Lunarville 7 compound, where before they discovered a brand new Mysteron complex being assembled in Crater Number 101 of the Humboldt Sea, situated on the far side of the Moon. The power source will also provide Spectrum with ample oppurtunity to somehow come into direct contact with The Mysterons themselves, to try and come to a peaceful settlement. All 3 men volunteer to carry out a full-scale expedition by infiltrating the complex and removing its power source, so it won't become of any harmless use and so the Mysterons will not be able to reconstruct the whole complex after it's destruction. However, the bomb which is transported to destroy the entire complex is set for 10:00 S.E.T. instead of the agreed Midnight deadline, by a Mysteron agent, disguising himself as a technician officer of Lunarville 4, the space-base that equipped and informed the 3 Spectrum officers, in ord

Captains Scarlet and Blue travel to the Himalayas to supervise and administrate Spectrum's new phase to monitor signals from a space satellite that has been launched into the orbit surrounding Mars, and to snap-shot high resolution detailed pictures of the planet, which will be relayed and received by the large mountain satellite station that the probe was launched from. The second satellite, with the first acting as a decoy, successfully lands on Mars, and sets to have Spectrum successfully completing the code-named ""Project Sword"" operation, but the whole carefully-planned out arrangement is placed under threat when one of the participating technicians ostensibly falls dead and is brought back to life by the Mysterons, with one instruction: to sabotage the observatory and to interrupt the satellites' transmission, before Earth comes to learn every single detail about the force, and prevent them from continuing the war of nerves and retaliation against the planet.

Concluding from where Crater 101 left of, Spectrum take a chance by commencing a maximum security operation to bodyguard radio communications expert, Doctor Kurnitz, from the Nash Institute of Technologies, up to Cloudbase to send a broadcasted voice message by Colonel White to the Mysterons base on Mars, in an effort to solve their differences, and to end the raging war of nerves between them. But the Mysteron pulsator stolen by Captain Scarlet during the expedition at Crater 101 is used as an explosive charge, to start a chain reaction on-board Cloudbase, which will no doubt utterly destroy the aerial base, and with Scarlet drawn away by Captain Black to prevent him from saving his fellow officers, the world-security organisation known as Spectrum, is condemned to be crippled.

A flaming 1000-feet inferno at a deliberately impaired oil-drilling rig, Rig Number 15, attracts the attention of Spectrum when the Mysterons explain their new threat to ""immobilize"" the international-security organisation, which would render all their aerial, sea and land vehicles from there daily used purposes. With the ultra-sonic oil wells or Spectrum's main oil refinery at Bensheba, not so far from Rig 15, as possible & potential targets, explosive specialist Jason Smith, is hired to extinguish the fire with his vast range of high explosive charges. Approaching the blazing rubble, Smith falls down in front of his tractor, and is reconstructed by the Mysterons when the tractor is forced forwards, burying the real Smith under the debris, but extinguishing the fire. The next day, the doppelganger Smith departs early from the site, leaving his original body near the downed rig, alerting Captain Scarlet that the Mysteron is on his way to the Bensheba oil refinery to annihilate it's ent

The Chief Test-Pilot of Slaton Air Base is killed and reconstructed in a staged car crash by Captain Black, but when two medical doctors pass by, they recover the test-pilots' original body, named Major Gravener, from the lake where the car ditched in, and successfully resuscitate him in a recovery constitute. Following this miracle, the Mysteron Major Gravener attempts to leave Slaton Air Base in a fighter jet, armed with a live nuclear warhead, but is stopped in-time when the base office is contacted by the hospital who revived the real Gravener. With Spectrum investigating the Mysterons' latest threat concerning the annihilation of the world capital, Futura City, they are alerted about the bewildering incident and use the real Gravener in a risky operation, as bait, to discover if the Mysteron's will fall for the Major Gravener, and spring a net on the wanted Captain Black, even when the Mysteron doppelganger is already dead.

Spectrum are involved with the safe, quiet transportation of escorting the world's leading astrophysicist, Doctor Congrad, to a Switzerland-located conference with the World President at Lake Toma. After boarding their mysteriously-empty flight, which could possibly be due to it being the ""slack"" season, with planes flying usually 3/4 empty, but with no hostesses around, Captains Scarlet and Blue become suspicious, and realise that they are trapped on-board the airliner, along with two tagging-along, & over-confident news-reporters, when learning there isn't any pilots flying the machine, immediately suspecting the Mysterons are controlling it. But that's not the least of their worries when the plane starts to descend rapidly, and its nose pointing straight in the direction of the French Alps.

Once again, the Mysterons target the Spectrum Angels in their latest act of retaliation, but it isn't actually one of the Angels, it's one of their home cities. Receiving a report from a biological research station on the outskirts of Manchester, England, regarding the theft of the phial of the K-14 virus. This is a revolutionary, & brand new strain, that has the capability to kill 10 million people. Captain Scarlet and Captain Blue start a timed race to find the station's research assistant suspsected of the theft, who is the only person to be granted access to it, Judy Chapman. Assessing that the forces' target is the Boulder Dam of Los Angeles, which the city's name stands for ""The Angels"", Scarlet places his non-indestructible life, in this particular case, on the line, to recover the phial, although he to faces imminent death.

The Hotspot Mining Complex, situated at the North Pole, is responsible for producing from the only existing natural source, commercial quantities of tritonium alloy, which is being used for constructing the nose casings for a rocket. General Rebus, the commander-in-chief of the Space Administration, is hoping to send the rocket to Mars, presumably to perform in-depth research assignments regarding the Mysterons. Captains Scarlet and Blue travel to the North Pole to act as security supervisors, in the inevitable time that the Mysterons may strike upon the complex, which they do when they take control over a maintenance engineer and instruct him to disconnect the massively high voltage current power lines between the booster power station and the tower. The 100,000 volt current is crucially-needed, as the heating rods located under the tower keeping the below-freezing ice at bay, and when the current is distorted, the ice will surround the tower, slowly but surely crushing the structure

A newly produced core reactor is being transported to the Manicougan Power Complex, which is near enough found near the Atlantic Seaboard of North America, which the Mysterons have announced that they will submit a ""heavy blow to the prestige of the world."" While conducting security checks within the designated area, it becomes aware that a missing, off-route Transporter 43, which has already inadvertently crashed over the edge of a demolished bridge, thanks to Captain Black's deliberate diversion of the planned route, is what the Mysterons are using to smuggle the reactor. With the core reactor already being aerially ferried in a shipping helicopter, and with the controller at the Expo 2068 construction site looking down at the barrel of Captain Black's hand-gun, Spectrum are back to square one before they can investigate the reactor situation. It becomes apparent however, that the copter's target is the Expo 2068 site, and evidence confirms that the thermal safety valve has been remo

Mervin Brand, a reporter for The Tribune newspaper, is killed in his jet by thunder-lightening while en route to the press conference with President Roberts. When reconstructed promptly by the Mysterons, so Tribune Control don't suspect that the real Mervin Brand has crashed and died, the Mysteron Brand continues his flight to the press conference, but is stopped in his tracks by the Angels, who have strict instructions to attack & destroy any aircraft violating the restricted airspace over the President's residence, due to his life being under siege by the Mysterons. His arrogance and egotism doesn't assist matters, as he believes the enemy foes preparing to kill him will not achieve their latest ploy of revenge, and ignores the fact that the Mysterons killed the Director-General of the United Asian Republic. Spectrum continue to secure his residence, but when the President reveals the new atomic-liner ship, built by the Trans-Pacific Shipping Corporation, is being named after him and

Professor Gabriel Carney, an awarded scientist for designing original electronics, is assassinated at his own gadgets-fulfilled home by Captain Black, in order for the Mysterons to use his skills and knowledge of the hi-tech subject to kill the three joint presidents of the Congress of Europe, additionally recognised as The Triumvirate of Europe. The names of those three men are: Conrad Olafson, John L. Henderson and Joseph Meccini, and this specific trio of men are apparently dubbed the most powerful figures on Earth, after the World President. The Mysterons elect Conrad Olafson as the first to be killed, whom is located in an underground suite, 40-feet underground Vandon Base, a maximum-security centre where plentiful Spectrum security personnel are scattered over, and in addition, the Angels commencing repeated aerial patrols over the area and Captain Ochre acting as the officer in charge of security. Their attention is diverted instantly by a realistically audible incoming military

An SKR-4 recovery vehicle is sent by the Euro-Space Tracker Station to destroy a live rocket, containing a malfunctioning destruct system, but ends being blown out of orbit and completely destroyed, when it collides with a considerably large meteorite. Re-produced and controlled by the Mysterons, it becomes the bombing weapon, which will accomplish the forces' newest target: the Najama Complex, a vital colossal desalination plant, situated by the foothills of the Andes mountains. Its purpose is to process seawater from the Pacific Ocean, and irrigate the interior, and without it, hundreds of square miles would regress to waste land. The complex is automated and requires very few personnel to administer the process, however it consists of vulnerable tanks, each containing liquid oxygen which would turn the whole valley into a ""blazing inferno"" if attacked with strong force. While the complex personnel are evacuated, Captains Scarlet, Blue, Magenta and Ochre are sent to set-up surveillan

The Australian Spectrum Hovercraft Centre, Koala Base, the university-style academy where several trainees are sent to brush up their skills and sit their practical and mental exams to become Spectrum hovercraft pilots, is the most likely place for Captains Scarlet and Blue to investigate, where several explosive sabotages have been made upon Koala's state-of-the-art hovercrafts, hence why the Mysterons latest threat states that there is a traitor within the world-security organisation, and that it threatens to tear it apart from within. Already settling on a few probable suspects, including the cadet leader, their suspicions rise even further when their room is set ablaze when sleeping. But when attending a routine test-run the next day, with one of their selected suspects, the duo discover that there isn't any traitors within Spectrum at all.

The Spectrum Cloudbase officers host a non-permitted party, excluding the ultimately strict Colonel White, to celebrate the 1st anniversary of the world-security organisation, with the assistance of an anonymous well wisher supplying the champagne, which has in fact been spiked with an organic compound which causes sporadic amnesia and general irresponsibility. After being severely cautioned by the Colonel, whom discovers the party and becomes very angry at his personnel for not receiving official permission to celebrate the anniversary, the Mysterons announce their intentions to destroy the World Navy Base of Atlantica, an invulnerable underwater complex protected by sea-to-air rockets and offensively-equipped submarines. Captains Blue and Ochre are handed the assignment to disband a wreckage which is being carried by heavy currents towards the Atlantica base, but the champagne has already taken control over them, turning them into juvenile rebelists. Captain Black manages to changeov

The threat that Spectrum have been awaiting for had to come, and Cloudbase being the principal headquarters of the organisation makes it an obvious target which would make seizing control over Earth a lot more easier for the Mysterons in order for them to complete their raging war of nerves, so the ""aircraft-carrier in the sky"" is targeted for destruction. With Symphony Angel stranded in the desert due to an unknown explosion on her Angel Interceptor, forcing her to eject, Captain Blue especially becomes agitated, for obvious romantic reasons, at the fact that she could die. With instructions for any aircraft entering a 100-mile radius of the airbase to be destroyed, and itself sealed from all external contact, the Mysterons themselves decide to visit Earth to obliterate Cloudbase personally, making this threat the most vengeful of all their past avengements.

While relaxing at a smart countryside restaurant during a late evening, Captain Blue, accompanied by Captain Scarlet, starts to feel strange after drinking a cup of black coffee. When Scarlet goes to fetch their coats, Blue instantaneously disappears, and when awakening, finds himself sitting in Lieutenant Green's chair back on Cloudbase, with a Spectrum Intelligence agent, who calls himself Colgan, sitting in Colonel White's chair. He explains that Blue has been absent without leave for three months, and must prove his identity by disclosing top-security information; the Spectrum cipher codes, before he can return to active duty. Without having to do this, Captain Blue instead story-tells three Spectrum assignments involving the Mysterons: the nuclear attack on London, the mission of destroying the Mysteron complex in Crater 101, and the prevention of a Mysteronised Commodore and his aid from slaughtering the Supreme Command of the World Air Force at the Scottish Glen Garry