Watch Cradle of Fear
This is a horror movie about revenge. A serial killer is caught and confined in a mental institution for life. Nobody knows that he has a demonic assistant on the outside. Kemper is a mentally deranged serial killer. When he is sentenced to a maximum security mental institution, the four families of the victims are relieved. The killer is angry that he has been confined, so he calls his demon to help him get revenge. This demon is not stopped by the walls of the institution. Each night, he slips out and kills another family member of one of the original victims. When the crimes are linked, the detective on the case is worried he will be the next victim.