The deal is that Beverly Garland, under the influence of sodium pentathol is recalling her story for a couple of head doctors. Her story is this: Her husband disappears on their honeymoon, and she spends years searching for him. She finally winds up at one of those typical (in the moves) mysterious old southern swamp homes where a mad scientist (George Macready) is trying to save accident victims with injections of alligator hormones (or something like that). This sounds like a perfectly reasonable idea to me, and it actually works. Unfortunately, there are certain . . . side effects. They aren't so bad, however, of you don't mind being scaly and green. Garland's husband doesn't like it, but Garland still loves him, anyway.
Macready thinks he can clear up the side effects with a simple blast of radiation, no more than one would use in the average cobalt bomb. You wouldn't expect this to work out well, and it doesn't. Or maybe it does, depending on your perspective. Hubby turns into a real ManGator, with a gator head and a human body. He's even wearing slacks, which is a nice touch. Seeing what he's become, he flees into the swamp on a dark and stormy night, pursued by Garland. She doesn't save him, though, thanks to what every movie like this needs: quicksand!
I forgot to mention that throughout the movie, Lon Chaney, Jr., is chewing the scenery at a fantastic rate. I'm surprised there was any of it left. He plays a crazy Cajun who hates alligator people.
They made a lot of movies like this during the '50s, and by "like this" I mean black and white monster movies. There's not really anything else like this one. Check it out.