This movie has a masterful mix of old-style gangster pictures and a mad scientist horror film. It's great! You get both Bela Lugosi and Boris Karloff doing their usual thing. Giving the movie some street cred. It plays out really smoothly and packs a big punch. It's the kind of quality I have grown to love from Universal.
A criminal with a secret stash of hidden money is paralyzed and dying after being involved in a hit and run during a get-away from a heist. A surgeon, and friend to a victim of that hit-and-run, performs a very risky operation. He transplants the brain of the criminal into that of his friend in hopes of recovering the location of that hidden money. However, he awakens a murderous and treacherous fiend that has a love for murder!
It can be argued that this has too much action to be a horror movie. Some parts feel like No Country for Old Men but others are thrilling and suspenseful enough to definitely be horror. People argue that this movie has serious flaws. Mostly with Bela Lugosi and Boris Karloff not sharing any scenes. Apparently, Karloff was hard to work with. However, none of that seems to take away from the entertainment value.
This isn't the best horror movie and it's really not that scary but I highly recommend it. It's a quality picture that shouldn't get swept under the rug or forgotten about. Not just because it is a Karloff/Lugosi movie. But also that it's a really absorbing and fun.