'The main danger, as I see it, is that you and I will be trapped here for the whole of the Christmas holiday!'

It's 19 December 1931 and Hercule Poirot and Inspector Catchpool are called to investigate a brutal murder in a Norfolk hospital. Catchpool's mother, the irrepressible Cynthia, insists that they stay with her nearby so that they can all be together for the festive period while Poirot finds the killer. Cynthia's friend is being admitted to the same hospital and she is convinced he will be the next victim.

Poirot has less than a week to solve the crime and prevent more murders, if he is to escape from this nightmare scenario and get home in time for Christmas. Meanwhile, someone else - someone utterly ruthless - has other ideas about what ought to happen to Hercule Poirot...