In the spring of 1923, the Honourable Daisy Dalrymple boards the Flying Scotsman, the famous London-to-Edinburgh train. On board, she meets an old schoolmate, Anne Breton, along with all her relatives. They are all en route to the deathbed of the family scion and notorious miser, Alistair McGowan. As it stands, Alistair’s will leaves the entire family fortune to his brother Albert, while each member of the family is hoping to convince the dying Alistair to change his will in their favor. Daisy, meanwhile, has her hands full when young Belinda Fletcher, the daughter of Detective Chief Inspector Alec Fletcher of Scotland Yard, stows away aboard the train. Daisy barely has time to take notice of the intricate family feud unfolding around her until the presumptive heir, Albert McGowan, is found dead—murdered—on the train. Now Daisy is surrounded by an entire family of suspects and becomes, once again, embroiled in an investigation in .