When a string of gruesome occult murders shakes their city, seasoned detective John Locke and his youthful partner Terri Keyes must set aside their disagreements to pursue the clues leading to a once-deserted asylum. Here, the new proprietor, Dr. Unnseine, is engaging in his own version of Nazi-influenced “medical experiments” on the unwilling patients. Among these inmates is the alluring yet lethal Annie Dyer, who might possess the crucial information about the murders—and the gateway to Hell itself—if Locke and Keyes can survive long enough to uncover it.