After his close friend, an affable and absent minded college professor (Stanley Ridges) is critically injured when a gangster runs him down, Karloff does what any other doctor would do – he transplants the gangster's brain into Ridges' head. Incredibly, Karloff manages to do this by himself, with no one at the hospital knowing about it. What's more, he doesn't need prior authorization from Ridges' health insurance company. In fact, Karloff does such a great job, there are no scars on Ridges, and he also maintains his full head of hair.

It seems the gangster has hidden 500 grand somewhere, so Karloff figures maybe he can coax the location out of Ridges, who is starting to act strangely. In short order, the gangster brain takes over, and Ridges (now looking about 30 years younger) goes on a killing spree, exacting revenge on his former gang. On occasion, he returns to his professor self. How will this all end? If you can ignore the stupidity involved, this is one of the most entertaining of the Universal horror flicks. Beautifully paced, never dull, the film benefits from a great Hans J. Salter score, with familiar themes he used over and over in multiple films. Karloff is fine as the doctor. But the real star is Ridges, who is outstanding in a dual role. Anne Nagel, as the gangster's girlfriend, is gorgeous. Murray Alper is very amusing as a confused bellboy. However, Bela Lugosi, billed second, is woefully miscast as one of the gangsters.

Black Friday is told in flashback. Scientist Boris Karloff has the ability to transfer brains. When a gangster's body is pretty much demolished in a car chase, he manages to get the mind of the man into another body. Apparently, there is a kind of rejection that occurs and soon we are led on merry chase involving gang activities, money, and a series of connections that are needed. The plot is convoluted because there is so much back and forth between emotions and prior memories. Karloff is set to be executed because he acted in a heroic way but when explained, it sounded ridiculous. As other have said, don't see this thinking there is going to be an ultimate confrontation between Karloff and Lugosi. They are on other poles. It's an exciting gangster/horror film and worth seeing.

This is a very enjoyable B-horror picture. However, considering that it starred Boris Karloff AND Bela Lugosi, you'd expect it to be even better--especially since some of their previous films together were classics (such as THE BLACK CAT and THE BODY SNATCHER). It just isn't up to the standards of their other films together--mostly because the plot is a bit dopey and because Lugosi's role isn't particularly memorable. Still, it is a dandy little film.

Here's the plot: Boris Karloff is a doctor and his friend, Professor Kingsley, is killed by a car driven by an evil gangster. However, in the accident, the gangster is paralyzed and is dying as well. Karloff makes a fateful decision--to transplant part of the gangster's brain into his dead friend and thereby keep at least a part of the gangster alive. The operation is a success and the professor seems okay at first, though after a while some of the gangster's personality starts to show. Karloff is a bit greedy and decides to try to bring out more of the gangster since he supposedly has half a million dollars and he wants to find out where it is hidden. The problem is that the gangster's personality comes through too well--making the kindly professor a cold-blooded killer!!!

Although Karloff and Lugosi get top billing, perhaps it should have gone to Stanley Ridges who played the professor/gangster. He seemed to have the lion's share of the screen time and did a wonderful job in both roles. I am surprised that they didn't give this role to Karloff or Lugosi--especially since Lugosi's part was rather small and he seemed miscast as just another gangster. Karloff definitely came off much better as the doctor, but if I had the story to do over again, I would have had Lugosi play the doctor, Karloff play the professor/gangster and Ridges play the lesser gangster--especially since that's what the fans would have wanted.

Now this miscasting isn't the only problems with the film but also the apparent "brainlessness" of the writing and direction. While transplanting personalities medically is silly, they didn't even try to carry it off well--having no bandages or incision marks on Ridges! He supposedly underwent massive brain surgery without a scratch!! Also, in a horribly telegraphed scene, just before the professor is struck by a car, as he's about to cross the street, the professor's wife tells him "to watch out you don't walk in front of a car"! No one would usually say that to anyone but a child and as soon as I heard that I KNEW what would happen next!!

Lackluster writing (at times),poor direction (at times) yet still a very compelling horror flick. It sure should have been better but still is a must-see for fans of Lugosi and Karloff.