A letter from an old friend, Antoinette Farnsworth, brings Jessica to a luxury island hotel, where she arrives just in time to investigate the sender's murder.
Tropes:
- Absence of Evidence: Jessica noticed that Alva Crane was wearing paste jewelry when they met, and knows that wealthy people often wear fake jewelry and put their real jewelry in hotel safety deposit boxes. Knowing that a professional thief would see that the jewels were fake too, Jessica believes that there was another motive behind Alva's murder. She and the inspector find her safety deposit box key in her room, but when Sheldon Greenburg (the hotel detective) pulls out the box it turns out to have no jewels in it. Jessica assumes that Alva was just faking her wealth...until she learns from the hotel manager that Alva really was rich. So it's very likely that she did have her real jewels in the box.
- Conspicuous Consumption: Jessica-as-Canfield flaunts her jewels in an effort to tempt whoever killed Antoinette into the light.
- Death Equals Redemption: Almost. Antoinette's father is very ill and both regrets his actions and wants to find his heir.
- Early-Installment Weirdness: This is Michael Hagerty's first appearance, and he's presented as a freelance troubleshooter who refers to being briefly attached to MI5. Later appearances have him as a full and current MI5 agent.
- Elopement: As a young lady, Antoinette ran off with a struggling poet. Her father, a wealthy vintner, annulled the marriage and sent the poet packing...but not before the couple conceived a baby, which he forced his daughter to put up for adoption.
- Foreshadowing: Despite the point of Jessica's Marguerite Canfield disguise being to lure out the jewel thief, she's never targeted (except by a purse snatcher). The thief turns out to be Greenburg ... who had already told her he knew her jewels were fake.
- Gem-Encrusted: Alva Crane covered herself in all kinds of jewelry, but Jessica could tell it was fake, and as she points out to the inspector, if she could tell, so could a professional thief.
- Gold Digger: Sven Torvald, who carried on with Antoinette Farnsworth and learned about her lost daughter. He learned that Antoinette had found her in Veronica, and after she was killed Sven put the moves on Veronica for her fortune.
- Green-Eyed Monster: Sheldon got sick of watching other people live the good life and decided to start living himself—by stealing over a million dollars worth of jewels and murdering their owners.
- Paper-Thin Disguise: Jessica passes herself as famed recluse Marguerite Canfield, in order to investigate Antoinette Farnsworth's death. However, the hotel detective recognizes her because he's read all of her books, and Hagerty knew Canfield before she became a recluse.
- Really Royalty Reveal: Veronica, the school teacher, is actually Antoinette's lost daughter. This makes her the heir to one of the largest vineyards in Europe. The contest she doesn't remember entering was a setup to get her onto the island.
- Red Herring: The gold-digging playboy who charmed the mother and tried to get his hands on Veronica's fortune is not the killer. In fact, the murder turns out to have nothing to do with Antoinette's fears that brought Jessica to the island, and the motive really was robbery.
- Saying Too Much: Jessica points out that Hagerty knows details of Antoinette's past that she shared with very few people. Hagerty turns the tables by pointing out Marguerite Canfield shouldn't know that either.
- Tracking Device: After Hagerty takes Jessica on a ride in order to confront her, one of the inspector's men manages to find them thanks to the doorman (another of the inspector's agents) slipping one of these into his car.
- Unequal Pairing: Eric and Myrna Brahm have to keep their marriage secret as company policy dictates that he can't fraternize with his employees. He plans to start a hotel of his own in a few months, though.
