Fatal Phantasm — Maggie Shayne

Jack's ex shows up out of the blue to ask for help with her dearly departed husband—who might not be so departed. Kiley—who didn't even know Jack had an ex, is determined to take the case from the rich widow, who is offering big bucks. A weekend in paradise seems like a fun break to Maya, except that both Johnny, the guy she's stuck on, and Joe, the guy she's pretending to be stuck on, are coming too. So the gang head to the private island mansion of the widow, where nothing is as it seems, and soon, they are cut off from civilization with no boat, no phone, and no help on the way, as a hurricane bears down on an island crawling with cultish killers who'll sacrifice anyone who tries to stop them from getting what they want. Immortality.