There's a murderer on the loose on a storm swept island cut off from the Scottish mainland. It's down to Losers Club, a quirky weight loss group led by the intrepid Penny Moon, to catch the culprit. When Old Archie the postman is shot and ends up in Mrs Hubbard's ice cream freezer, the whole island is aghast. Especially Mr Hubbard, who objects strongly to having to move all the ice lollies into the other freezer. Newly divorced and desperate to make a life for herself and her teenage children, Penny Moon arrives on Vik just in the nick of time, before the island is cut off by a storm. Her weight loss business doesn't have the best of starts, when a series of blunders leads to it being called Losers Club. However, it does have the best of people - a decent, disparate bunch who decide that, with the police unlikely to arrive any time soon and a murderer on the loose, it is down to Losers Club to investigate. As they dig deeper into the mystery, they uncover a dark secret, kept by the older islanders for almost half a century. A secret that has come back to haunt them and threatens their very existence.