When Hercule Poirot, a well-known inspector and an eccentric, but very likable, Belgian refugee from the Great War, discovers that Emily Inglethorp, his wealthy benefactress who helped him through his new life, has been found dead, poisoned with strychnine, he sets out to solve the crime. But there is a problem. The main suspects are close relatives who can't or don't want to cooperate.

This mystery novel follows Anthony Cade, a man who unknowingly finds himself in the middle of an international conspiracy and a murder investigation after accepting a simple delivery job from an old friend. As Cade slowly begins to realize his predicament has potentially put him in danger, he begins his own investigation into the strange series of events just as Inspector Battle of Scotland Yard begins the main, official investigation.

It’s December 19, 1931. Hercule Poirot and Inspector Edward Catchpool are looking forward to a much-needed, restful Christmas holiday, when they are called upon to investigate the murder of a man in a Norfolk hospital ward. Cynthia Catchpool, Edward’s mother, insists that Poirot stay with her in a crumbling mansion by the coast, so that they can all be together for the festive period while he solves the case.

Pretty, young Anne came to London looking for adventure. In fact, adventure comes looking for her - and finds her immediately at Hyde Park Corner tube station. Anne is present on the platform when a thin man, reeking of mothballs, loses his balance and is electrocuted on the rails. The Scotland Yard verdict is accidental death. But Anne is not satisfied. After all, who was the man in the brown suit who examined the body? And why did he race off, leaving a cryptic message behind?

In a remote house in the middle of Dartmoor, six shadowy figures huddle around a table for a seance. Tension rises as the spirits spell out a chilling message: "Captain Trevelyan...dead...murder." Is this black magic or simply a macabre joke? The only way to be certain is to locate Captain Trevelyan. Unfortunately, his home is six miles away and, with snowdrifts blocking the roads, someone will have to make the journey on foot....