Their Last Vacation, a suspense noir by Bruce Allsman

As a reward for her work at a recent charity drive, Allison McCain, a psychiatrist in her mid-thirties, accepts an invitation from Robert Yates, a billionaire, to an all-expense-paid vacation at a remote tropical island, somewhere off the coast of Central America. At the island, she stifles an uneasy surprise when she meets the other guests: Christine Lambert, Steve Allen, and Dan Morrison, her old college friends. Recalling memories of their shared tragic past, she questions Robert's motive for bringing them together but is unable to confront the billionaire since he had left in the helicopter soon after her awkward meeting. The situation escalates the next morning when they find the body of Steve floating face down in the swimming pool. She feels that his murder is only the beginning and unless she uncovers the killer's identity, all of them will be dead within the next few days.