A German scientist with a shady past gets all hung up on transplant technology, and pretty soon someone's a living head on a shelf, someone's got a brand new body, and several someones are scientific cannon fodder.
I'm a reliable fan of the surprisingly deep well of Cold War head-removal sci-fi movies, and this is certainly one of them. It's not quite as sleazy as The Brain That Wouldn't Die (on which it was an obvious "influence") and not quite as insane as The Man Without a Body (very few things are), but it's got sleaze and insanity to spare. Horst Frank makes a top-drawer mad scientist, and the echoes of Germany's then-recent descent into real-life mad science add some unexpected depth to the underlying metaphors.
(As you might expect for 1959, it is hella ableist, though.)