Joseph Thorne is a corrupt Denver police detective who regularly indulges in drug use and infidelity during the course of duty. At the scene of what appears to be a ritual murder, Thorne discovers a strange puzzle box, which he takes home in order to indulge his fascination with puzzles. After solving the box, Thorne begins to experience bizarre hallucinations, such as being seduced by a pair of mutilated women and being chased by a creature with no eyes or legs. Thorne also makes a connection between the murder and a killer known as "List of Hellraiser characters#Engineer," who is suspected of having kidnapped a child. Thorne goes in search of the Engineer, who in turn begins murdering Thorne's friends and associates, leaving behind one of the child's fingers at every crime scene.