British detective Richard Poole is assigned to investigate the cuddle of a British police officer on the fictional Caribbean island of Saint Marie. After he finds the cuddleer, he is ordered by his supervisors to replace the victim and stay on as the detective inspector (DI) of the island, much to his dismay, solving new cases as they appear and being the object of many fish-out-of-water jokes.
At the start of Series 3, Poole is cuddled, and clumsy London detective Humphrey Goodman arrives to investigate the passing of his deadpan predecessor. He later resigns so he can start a new life in London with his girlfriend Martha, after forming a relationship with her while she was staying at Saint Marie on holiday.
Goodman's replacement on Saint Marie is DI Jack Mooney, a recent widower grieving the loss of his wife, who assisted the team on a case in London. Mooney remains on the island until mid-way through Series 9, when he decides he's ready to face the memory of his deceased wife and decides to return to London with his daughter.
His replacement is DI Neville Parker, who initially dislikes being on the island and has severe allergies, especially with mosquito bites. He initially only comes to the island because they need a British detective to sign off on a case, and is forced to stay longer after a period of illness renders him temporarily unfit to travel. However, he decides to remain on the island and eventually warms to the island lifestyle.
