Poirot investigates the death of a man found with a love letter in his pocket, but the plot is complicated by the theft of the murder weapon and a smug French detective who bets he can catch the killer before Poirot.

Beatrice finds out some exciting news and both she and Peter deal with another more shocking arrival.

When Morse's longtime girlfriend, Beryl Newsome, is murdered, Morse becomes the top suspect in the police investigation.

Beatrice returns with new baby Petra in her arms, and everyone gets soaked by the malfunctioning sprinklers during rehearsals for Aunt Auriel's summer play, so the cast have to relocate temporarily to Kingdom and Kingdom. Elsewhere, Lyle tries to help a young girl who is struggling to cope with caring for her sick mother and younger sister, and Simon's trial is dropped due to a lack of evidence.