Using stolen glands from unsuspecting donors, Dr. Georges Bonnet (Anton Diffring) has managed to cheat death, remaining youthful and virile on the outside despite his advancing age -- that is, until his internal clock catches up with him. Crippled by an increasingly unstable mind, Bonnet sets his sights on winning the heart of a former flame (Hazel Court) who's in love with another doctor (Christopher Lee).