I, Monster (1971, d. Stephen Weeks)
A turn of the century British doctor is on the verge of a medical breakthrough: he’s devised a drug capable of releasing deepest inhibitions. But when the good doctor uses the drug on himself, he releases a dangerous alter ego. With each transformation, he becomes more powerful and hideous. The doctor is caught in a deadly struggle with his inner self.
If this sounds to you like a movie version of Robert Louis Stevenson’s “Dr. Jekyll & Mr. Hyde”, you’re spot on, as the British would say. In addition to starring both the greats of Hammer Horror Christopher Lee and Peter Cushing, it’s a fairly loyal translation of the original story, accept for the main character’s names.
If anybody knows what happened with this movie in getting made with the name change, please comment.