Ruth Kettering is found murdered aboard a luxury train, and it is soon discovered that her rubies are also missing. The prime suspect is her husband, but Hercule is not convinced, so he stages a reenactment of the journey, complete with the murderer on board.

Framed in the doorway of Hercule Poirot's bedroom stands an uninvited guest, coated from head to foot in dust. The man stares for a moment, then he sways and falls. Who is he? Is he suffering from shock or just exhaustion? Above all, what is the significance of the figure 4, scribbled over and over again on a sheet of paper? Poirot finds himself plunged into a world of international intrigue, risking his life--and that of his 'twin brother'--to uncover...

Tommy and Tuppence Beresford, two unlikely spies, help to defend their country by trying to rout out two highly placed Fifth Columnists. When Tommy is asked by the British Intelligence Service to go and stay at the Sans Souci guest house he is astonished to see Tuppence there. The mission: to identify which of the other guests is N and which is M. - Publisher.

Hercule Poirot investigates the double suicide deaths of Lord and Lady Ravenscroft that occurred twelve years ago. There are hints that it was not suicide after all.

Elinor Carlisle and Roddy Welman are the model English couple, perfect companions set for a life of ease when they inherit Aunt Laura's considerable fortune. But a poison pen letter begins a chain of events which is to end in tragedy. Convinced that Mary Gerrard, a childhood playmate of Elinor's, is attempting to ingratiate herself with her aunt for financial gain, the pair travel to the family home to investigate. They find no evidence but Roddy...

Hercule Poirot solves a baffling murder at an English country home.