A call for help from a former colleague leads Maine game warden investigator Mike Bowditch and his girlfriend Stacey Stevens to a research station far off the coast. In this 13th outing (after Dead by Dawn), the biologists are being stalked by a mysterious boatman who they suspect is trespassing on the refuge late at night. After two researchers are murdered and another disappears, Mike and Stacey must travel to another island, where someone in the village knows more about the killings than they dare admit.