Five young women traveling with their friends have gone missing on the island of St. Thomas over the last year. The most recent only a few days before PI Riley Sullivan travels there with her husband, Det. Luke Morgan, for their best friend's wedding. Vowing to not get involved, all Riley wants to do is focus on the wedding. Fate had other plans.
When a victim's body washes up on the beach near their hotel, Riley feels like she has no choice. The investigation is an uphill battle, bringing Riley and Luke face-to-face with the local detective who has deemed all of the cases runaways. It seems like he has something to hide as do the suspects they quickly identify - a disgraced British diplomat, a tech billionaire, a scuba instructor, and locals who date women for sport.
Riley and Luke must work together to uncover which one of them is behind these disappearances, but the clock is ticking and they only have so much time before their vacation is over. The race is on to stop a killer before he strikes again.