Poirot and Hastings are at Lake Windermere for an attempt on the world speed-boat record. An elderly widow is hurt by falling down stairs, then later killed by poisoning with phosphorus.

A string of thefts at a student hostel run by Miss Lemon’s sister ends in death and Poirot has a number of plots and sub-plots to untangle. A certain mouse is the only witness to a string of murders.

Poirot believes his dentist was murdered and Japp thinks it was a suicide.

On an airplane, flying from Paris to London, one of the passengers is killed by a poison dart while Poirot sleeps.

Beside the bodies of three murder victims lies a copy of the ABC Railway Guide.

The London and Scottish Bank is sending a huge shipment of Liberty Bonds to New York on the liner Queen Mary. Poirot, who suffers terribly from sea-sickness, is asked to see the bonds safely across the Atlantic.

Poirot is called in when the British Prime Minister and his secretary are kidnapped in France on their way to a League of Nations conference – and he is given just a day and a half to solve the case.