Forget Frankenstein — the weirdest monster movie ever to star Boris Karloff has got to be 1940's The Ape, as proved by this clip. Karloff plays Dr. Bernard Adrian, a mad scientist who's trying to create a serum to cure sweet young Frances Clifford's polio — but to do that, he needs lots of human spinal fluid, and where can he get it? Meanwhile, in an unrelated development, an escaped circus ape is running around ripping people's spines out. How do these storylines ever intersect? Watch the clip and find out.
In the climax, as you can see, the girl finally proves she can walk right after the police have uncovered the identity of the killer ape. The shock of seeing Dr. Adrian un-aped and dying finally breaks through her mental inhibitions, and she's able to stagger out of her chair for the first time. Too bad she got the doc killed in the first place, by shouting at the top of her lungs that a killer ape was heading for his house.