For the world, Doctor Brewser (Bela Lugosi) is presumed missing, only
his sister Agatha (Minerva Urecal) & his friend doctor Randall (Henry
Hall) knows that he actually hides out in a secret lab in his own house.
But why does he do it ?
He has made a wicked self-experiment involving the spinal fluid of an
ape, & naturally (well, naturally in the B-movie realm) this
experiment has turned him into a half ape. So consequently he locks
himself into a cage with a real ape (Emil Van Horn) - really. But still,
he is a (mad) scientist, so he has soon figured out a way to reverse the
process of the apes' spinal fluid: inject himself with human spinal fluid
... theere is only one tiny catch, deriving spinal fluid from a human
would kill that person - & thus Doctor Randall refuses to cooperate.
So Doc Brewster goes on a little trip on his own & takes his monkey
with him (they are even seen talking to each other in ape language) ...
& the first person he kills is Randall's own butler.
With the human spinal fluid injected, Doc Brewster immediately feels
better (which is mainly represented by the fact that he can suddenly stand
up straight), but alas, that condition doesn't last, & he figures he
needs more, much more. So he & his ape go onto a killing spree,
killing pretty much everyone they eventually pick up.
But when Doc Randall refuses to make the infusion, partly due to his
conscience, partly because the poice have somehow picked up his trail,
Brewster kills him too in a fit of rage.
Meanwhile though, reporter Carter (Wallace Ford) & his female
photographer Billie Mason (Louise Currie) have picked up Brewster's trail
& soon, independently from each other, break into his house. But when
searching the house, Billy accidently knocks Carter out, then is knocked
out herself by Brewster who plans to make her his next victim. By that
time though, the police ahve also arrived, & somehow Brewster's ape
has gotten out of his cage ... & finally, brewster is killed by his
own ape, while Billie is saved.
One of these wonderfully silly Monogram horror films that
doesn't make any particular sense but has everything a proper pulp story
needs: a mad scientist, an ape, a girl reporter, a secret lab & of
course sliding doors & hidden passageways. All that is tied together
in a fast-paced story, with Lugosi making (as usual) an excellent mad
scientist, & Wallace Ford & Louise Currie are quite good as
B-movie hero & heroine, too.