It's Jesse's birthday, and as he says it's a" big birthday" and he's not taking it well; in fact he has announced that anyone who mentions a certain number is in danger of being bitch-slapped. His partner Tim Mallory has just the perfect birthday gift to cheer Jesse up, a Caribbean cruise. Along with Tim and Jesse will be the gang from Bath, Maine as well. But before they can sail away they must try to solve a sixty year old missing person's case. In 1953 two teenage boys set out to visit friends in the next town and then seemingly disappear into thin air.
Once on the cruise Tim and Jesse look forward to relaxing with their friends in the sunny Caribbean, but when a passenger disappears in the middle of the ocean, Tim and Jesse are asked to look into the disappearance.
A chance notice on the ship's bulletin board compel Jesse his cousin Monica to confront their family's Spiritualist past and it's anything but smooth sailing for the two cousins.