Amid a battle over the dead aunt's fortune, detective Hercule Poirot investigates the secret pasts of all possible suspects and nearly becomes a third victim of the killer. Glamorous Arlena Marshall, vacationing with husband and stepdaughter in a hotel on Smuggler's Island, is found strangled to death. The famous Belgian detective finds that at least six of the other hotel guests had motives for the murder, but his usual faultless reasoning eventually discovers the murderer along with some surprises. A young girl pleads with Hercule Poirot to prove the innocence of her dead mother, who was convicted sixteen years earlier of murdering the mother's husband, a famous artist. Poirot accepts the challenge and solves one of his most complicated cases.
Death is no laughing matter, especially at a luncheon party in an English country house.
When Poirot finds a handsome young man on the edge of the swimming pool with blood dripping into the water, he thinks his hostess is staging a 'murder' for his benefit. But he soon realizes the man is really dying. He decides to undertake twelve cases that have a special reference to the twelve labors of the ancient Hercules. Each case appears to be more baffling than the last. Because Hercule Poirot arrives too late to head off the fate of a rich and beautiful young widow, he is left with the task of solving a maddening and macabre mystery.