Professor Cory (Lew Ayres), living out in the desert with is wife Janice and alcoholic assistant (Gene Evans), is successful in keeping a monkey's brain alive in a special tank (it looks like a fish tank). When a millionaire industrialist named Donovan is fatally injured in a nearby plane crash and he's called to the scene because he's the closest doctor available, he decides to take advantage of the opportunity and removes the man's brain. The brain still registers brain-wave activity. Soon, Cory is able to communicate with the brain - and the brain, in turn, is able to take over his body. He even starts taking on characteristics of the millionaire, from his ruthlessness to his distinctive limp. The brain starts to grow in size and power - and is soon able to take control over anyone. Will the doctor's wife and friend be able to destroy the brain before it destroys them?
This is an excellent sci-fi movie, particularly for the time period in which it was made.
I believe this is the third adaptation from the Curt Siodmak novel - and with the current state of every-other-move being a remake nowadays I think it's probably time Hollywood makes another Donovan's Brain movie?