Evil Under the Sun

Whilst holidaying at a secluded hotel in Devon, Hercule Poirot notices former actress Arlena Marshall flirting with Patrick Redfern, despite both of them being married to other people. One morning, Arlena heads out for a private rendezvous at Pixy Cove; everyone initially assumes she has gone to meet Redfern, but he emerges from the hotel looking for her moments later. He and Miss Emily Brewster row around the island and find Arlena lying dead. An examination by the local police surgeon reveals she has been strangled.

Both Poirot and the investigating officer, Inspector Colgate, interview the possible suspects about their movements during the morning. Poirot learns that Emily Brewster was nearly hit by a bottle thrown from one of the guest rooms, while the hotel chambermaid recalls hearing someone running a bath at noon. Poirot also notes the aroma of Arlena's perfume inside a hidden cave near Pixy Cove.

Looking for similar cases, Poirot learns of the strangulation of Alice Corrigan; she was found by a local teacher, at a time for which her husband Edward had an alibi. Poirot is supplied with a photo of both Corrigan and the teacher; later, he invites most of his suspects to a picnic, at which he secretly observes their behaviour and tests their reaction to heights. Following the picnic, Arlena's stepdaughter Linda attempts suicide with Christine Redfern's sleeping pills. Poirot reveals that Linda has been experimenting with voodoo, and believed her "spells" killed her stepmother, whom she hated and mistrusted.

Bringing together the suspects, Poirot denounces Patrick and Christine Redfern for Arlena's murder. Arlena had been killed to prevent her husband from learning that Patrick had conned most of her fortune away. The murder was well-planned to falsify the time of death; while Christine was at Gull Cove with Linda, she set Linda's watch forward twenty minutes, asked for the time to set her alibi, then returned the watch to the correct time. Afterwards, Christine returned to her room and applied fake suntan makeup, which she concealed from sight, before tossing the bottle out the window, where it inadvertently landed right next to Miss Brewster. Sneaking down to Pixy Cove via a long ladder the hotel had fixed there for tourists, Christine made certain Arlena saw her; Patrick had instructed Arlena to hide should his wife turn up before their rendezvous. Once Arlena was deep in the cave, Christine impersonated the dead body to fool Brewster, who immediately left to get help while Patrick remained behind. After Brewster's departure, Christine rushed back to the hotel to remove the makeup. Patrick then called an unsuspecting Arlena out and strangled her.

Poirot reveals that Christine lied about having a fear of heights, as she easily traversed a suspended bridge during the picnic. Linda's attempt at suicide was also provoked by Christine. As further proof, Poirot reveals that the photo from the Surrey Police identifies Patrick as Edward Corrigan, who killed his wife Alice, and Christine as the teacher who evidently claimed to have found the body before the murder actually had been committed. With the case closed, Poirot reassures Linda she did not kill Arlena and predicts she "will not hate (her) next step-mother", as her father has rekindled a romance with his childhood sweetheart.