Dr Ernest Sovac (Boris Karloff) is reaching the end of his life, imprisoned on Death Row for murder. Tonight he goes to the electric chair, but as he walks past the press, he stops and hands one reporter his notes, telling him this is because his was the only newspaper which treated his story with balance. As Sovac is strapped in, the reporter leafs through the notes, which elaborate his side of the story and how he went from a university lecturer to a criminal, and all because of what happened to his good friend Professor George Kingsley (Stanley Ridges)...
Friday the Thirteenth didn't really take off as a day synonymous with horror until 1980 and the slasher of the same name was a hit, and this film didn't do much to assist as there's but the briefest mention of the date near the start and then the rest of the story has absolutely nothing to do with it. That's not to mention that it's more of a gangster movie with a fantastical twist, despite the appearance of two of the era's most celebrated shocker stars in Karloff and Bela Lugosi. Neither really get the best role, as that goes to Ridges as the schizophrenic centre of the thrills.
What happens is that Sovac, desperate for cash to supply his funding for a new laboratory, hits upon an idea when poor old Kingsley is run over by two gangster cars while crossing the street. One gets away, but the man who crashes into him is knocked unconscious at the scene and in the ambulance with them both Sovac realises that to save his friend he must perform a brain transplant. Now, any sensible science fiction flick would have him transplanting the professor's brain into the gangster's body, but nope, not here, it's the other way around.
Science is not this film's strong point as you can see, especially as now Kingsley's body has the gangsters' brain in it he still acts like Kingsley - until Sovac wears him down and manages to bring out the bad guy's personality on a trip to the big city. There's a stash of hidden loot to be found, and only the evil side of Kingsley knows where it is, and not only that he's out for revenge against the gang, led by Lugosi, who wanted to kill him. So every so often he'll have a turn, or hear a siren (which always sets him off), and go a-strangling.
Originally the film had Karloff cast as the Professor and Lugosi as the doctor, but it didn't work out and Ridges was brought in which is fine as he's the best thing in it. Black Friday is unusual for having Karloff's character not as well-meaning yet misguided, but pretty despicable and only out for his own gain, which at least is a variation on the roles he had become typecast in by this stage. Sadly, he and Lugosi have no scenes with each other as Lugosi is lost in a supporting role that any tough guy actor could have played, but Ridges makes for an interesting yet tragic villain and if you can forgive the preposterous plotting the film is a fairly high quality B movie.