Christopher Lee stars in this Amicus production of “Dr. Jekyll & Mr. Hyde” where the names have been changed to Dr. Marlowe and Mr. Blake. Lee as Dr. Marlowe experiments with intravenous drugs that are suppose to release inner inhibitions. So comes forth Mr. Blake (also Lee) who gets more monstrous with each transformation. Peter Cushing plays his friend and colleague, Dr. Utterson.
Acting
Lee's physical transformation work — subtle, then suddenly NOT.
Production
Fog-drenched London sets on obvious budget, somehow more haunting.
Practical Effects
Progressive monster makeup that ages worse than the themes.

Director
Stephen Weeks
Trivia, insights & behind the scenes
Stephen Weeks was only 22 when he directed this, making him one of Britain's youngest feature directors — explains the ambition exceeding the budget.
Amicus was Hammer's scrappy rival; this film's renamed characters let them dodge Universal's copyright on the Stevenson adaptation while keeping the exact same story.