It's Halloween, "the craziest day of the year," and the detectives are trying to solve the grisly murder of two young women, each dressed in odd clothing and barring a strange symbol on their wrists. With the help of an FBI agent who has been investigating identical murders over the past two Halloweens, they discover that the girls were killed by a mysterious cult. When one of their own is abducted, the detectives are sent on a frantic race against time to save their friend and stop the ritual, the results of which could prove devastating.