It's December in Cornwall, and Mousehole harbour is illuminated with its famous Christmas lights. Ally Bright is among the crowd listening to the carol singers--and then to the piercing screams that rip through the darkness. A body has been found, brutally murdered and dumped in a fisherman's boat. The victim is chef JP Sharpe and there is no shortage of people who might have wanted him dead. Eager for a new case for The Shell House Detectives, Ally calls ex-cop Jayden, but he's keen to leave it to the police--until a letter in Sharpe's pocket draws them into a seemingly unconnected family mystery. As they take on this highly charged mission, the duo can't help scrutinising the murder suspects. Who among the close-knit community has reason to kill, and how far will they go to protect themselves? As fear spreads, Ally and Jayden need answers--fast. Could the letter offer a clue to the murder case or will it reveal a terrible truth? And when a new witness comes to light, Jayden closes in on a desperate killer... but can he warn Ally in time?