A prisoner is killed while being transferred to Saint Marie — all while handcuffed to D.I. Richard Poole. To preserve his job and his dignity, Poole must find out who on the ferry killed the victim when half the island wanted him dead.
Tropes:
- Foreshadowing: A passenger on the boat tells Poole they like Agatha Christie's "Murder on the Orient Express," a novel about a man murdered by stabbing. Then shortly after Poole's prisoner is stabbed to death.
- Impersonating an Officer: Leon Hamilton.
- Kill and Replace: A short term version with Leon Hamilton and Vincent the prison guard.
- Masquerading As the Unseen: Poole eventually realises that very few people on the island had ever met Leon Hamilton face to face, and so has the one investor he knows actually met him brought to the final confrontation to confirm his suspicions.
- The Mole: The killer pretends to be the prison guard responsible for Leon in order to stay above suspicion.
- ShoutOut: A passenger on the boat tells Poole they like Agatha Christie's "Murder on the Orient Express," a novel about a man murdered via stabbing from impersonators. Then shortly after Poole's prisoner is stabbed to death and the case involves impersonations.
- Spotting the Thread: Poole notices that before he died, Leon Hamilton was seasick and also claimed he had never been to Saint Marie; his wife later mentions that he spent a lot of time sailing around the island.
- Who Murdered the Asshole: Leon Hamilton was in jail for a con which victimised half the population of the island.
- You Have Outlived Your Usefulness: Combined with He Knows Too Much, Leon kills his wife after she helped him fake his own death. It's implied that her murder was part of the reason he made the plan in the first place rather than simply wait out the last six months of his sentence.
