I, Monster

19th-century London psychologist Charles Marlowe experiments with a mind-altering drug. He develops a malevolent alter ego, Edward Blake, who his friend Utterson suspects of blackmailing Marlowe.

I, Monster is a 1973 horror movie directed by Stephen Weeks, starring Christopher Lee, Peter Cushing, Mike Raven. It holds an IMDb rating of 5.7/10 from 2,282 votes and runs 1h 15m.