A beautiful model, Marlis, is horribly murdered on a Caribbean island. Her sister Terry arrives and, with the help of Fred, a writer, discovers that the dead woman was another model, and not Marlis. They learn that the natives live in fear of a terrible rat man but put it down to local superstition, until the real Marlis is killed by a being with the face of a rat. Fred kills it, but more rat men are preparing to attack…