It was supposed to be the best-ever girls’ trip: five days, four friends, one luxury yacht, no parents. But on the final night, as the yacht cruised the deep and dark waters between Florida and Grand Cayman, eighteen-year-old heiress Giselle vanished. She’s nowhere to be found the next morning even after a frantic search, until security footage surfaces... showing Maggie pushing her overboard. But Maggie has no memory of what happened. All she knows is that she woke up with a throbbing headache, thousands of dollars in cash in her safe, a passport that isn’t hers, and Giselle’s diary.

And while Maggie had her own reasons to want Giselle dead, so did everyone else on board: jealous Viv, calculating Emi, even some members of the staff. What really went down on the top deck that night? Maggie will have to work her way backward to uncover the secrets that everyone—even Giselle—kept below deck or she’s dead in the water.