Mary visits Highclere Castle, the real-life Downton Abbey, home to the eighth Earl and Countess of Carnarvon and renowned as the setting for some of the most lavish and influential weekend house parties in history. Mary discovers what it takes to keep a home like this going in today's world, meeting everyone from the family to the house staff and the estate's loyal posse of gamekeepers. Inspired by what she discovers, Mary takes to the estate kitchen where she creates a delicious spread, from raspberry tartlets to gamekeeper's stew and an elaborate menu for a grand finale dinner.

Mary visits Scone Palace, the crowning place of Scottish kings and the epicentre of Scottish history, where she is invited to help Lady Mansfield prepare for a special dinner with traditional Scottish reeling in the palace where Prince Albert and Queen Victoria were once amused. Mary enjoys salmon fishing on the family's private stretch of the Tay, and the regal pastime of Highland deer stalking with William, the future Earl of Mansfield, as well as the family's long-serving gamekeeper. Inspired by such royal history, Mary rustles up Scottish classics in the estate kitchen, including venison wellington, cock-a-leekie soup and cranachan.

Mary visits Powderham Castle in Devon to spend time with the Earl and Countess of Devon and their two young children, who are reinventing the Earldom for the 21st century. Mary's time with the family reveals stories of romance and tragedy as she discovers more of this extraordinary home. In the castle's historic kitchen, Mary prepares a Devon cream tea, before making a delicate peach posset for a Midsummer Eve woodland party the family are throwing to celebrate their two year anniversary at the castle.

In the final episode of the series, Mary visits Goodwood House, home to the March family, famous for their iconic horse racing and motoring events. She is taken on a thrilling lap of Goodwood motor circuit by Lord March, before attending one of his infamous dinner parties where 300 guests dine in style in splendid state rooms. Mary also learns more about the Estate's organic farm, before preparing a Coq-au-Vin and a four tier cake for a cricket tea set in one of the oldest cricket clubs in the world. Last in the series.