While searching for a philanthropist's missing wife, the team comes up against a grifter ring running a web of sophisticated “Sweetheart Scams”. Now, Nate must learn how to steal hearts… or risk losing Sophie's for good.

Investigating a spy-ring Colin Race comes to Wilbraham Crescent, where he literally bumps into agency typist Sheila Webb, as she comes flying out of number 19, the home of blind ex-teacher Millicent Pebmarsh. Sheila has discovered the body of a man whose identity proves hard to confirm, surrounded by four clocks, stopped at the same time. Miss Pebmarsh does not know the man and did not ask for the services of Sheila, who is the initial chief suspect. However, as Poirot is brought in to assist Inspector Hardcastle in the case, and the murderer strikes again, Poirot comes to realise that the man was killed elsewhere and brought to Miss Pebmarsh's house. The neighbours claim to have seen nothing but Poirot believes one of them may have had a secret which was worth killing for and sets out to unmask them, as well as explaining the significance, if any, of the clocks. At the same time Colin solves his investigation but with mixed results.

With her son Trevor due back from the missions abroad for the first time in four years, Agnes wants to make sure that this Christmas is a truly special celebration, with her whole family together. Dermot finds himself under pressure to spend Christmas with his wife's family.