Notes: Twentieth-Century Fox. 67 minutes.
Peters -- Bela Lugosi
Harrigan -- Harry Ritz
Mulligan -- Al Ritz
Garrity -- Jimmy Ritz
Walter Stevens -- Lionel Atwill
Norma Denby -- Anita Louise
Kitty -- Patsy Kelly
Jack Marsden -- Edward Norris
Seaman -- Wally Vernon
Stranger -- Joseph Calleia
Conway -- Paul Harvey
Director -- Allan Dwan
Screenplay -- Rian James and Sid Silvers
Producer -- Jack Broder
Associate Producer -- Harry Joe Brown
Based on a play by -- Ralph Spence
Summary: Headlines read: "Gorilla, Maniac Murderer Terrorizes Suburbs: Police Claim Gorilla a Professional Killer -- Is It a Man or Beast?" and "Westchester Terror-Stricken as Murderer Makes Good His Threat."
A woman, Kitty, is lying in bed reading and sighing over Romeo and Juliet as an ape's arm reaches in her window and plants a note on her. She sees the arm and flies into a frenzy, running through the house screaming. The butler, Peters, tries to silence her, and the master of the house, Walter Stevens, after reading the note -- an image of a gorilla's paw with the warning that he's the next to die -- receives a clandestine phone call, seeming to indicate he's being blackmailed. He must raise a quarter million dollars by tomorrow. The silhouette of a man in a hat appears outside his window. He then sends a "radiogram" saying he can't meet someone at the boat but must at home, signed, "Fondly, Uncle Walter."
Miss Norma Denby and her fiance Jack -- they'll be married the day after tomorrow -- join Stevens. Uncle and niece are joint heirs in the terms of her father's will. Walter reports about the gorilla note and admits he has not contacted the police. This whole business gives Norma "the creeps." Kitty tries to quit but Walter won't hear of it.
Three detectives (the Ritz brothers) hired by Stevens briefly try to question Peters and Stevens and tremble at the mention of the gorilla. Peters claims there's something wrong with Jack's car. The night is stormy and a figure at the window sees Stevens open a wall safe behind a painting. The detectives try to question Kitty, but she spent the night with Shakespeare, who has been dead for hundreds of years.
Stevens proposes liqueurs in the study when another threat about midnight tied to a rock is thrown through the window. Elsewhere an ape is released from its cage. The radio insists that Stevens has five minutes to live. Footsteps upstairs draw the detectives away, but Peters says he was just bringing down a trunk from the attic. At the one-minute warning from the radio -- "You have one more minute, Walter Stevens" -- Stevens pulls out a gun. The clock strikes midnight. Jack tries to call the police but the phone is dead. The lights go out. A moment later, Stevens is gone and Peters is mysteriously in the room. A gorilla arm, seen only by Kitty, emerges slowly from a closet and threatens Norma. An unknown sailor's body is found in the closet, not quite dead. Jack seems to be working on a theory as the detectives try to re-enact the crime. One of the detectives disappears from a chair, then another. When Kitty is next in the chair, the lights go back on and she finds herself in the room not with the detective but with Peters.
The chief detective, Harrigan, emerges from the closet, meeting a man claiming to have had his car break down and needing the phone. This stranger handcuffs the detective and visits the wall safe. Jack releases the detective and the two other detectives emerge from the closet. When they look for trap doors, Stevens has a brusque visitor, there to collect $250,000 he says Stevens has been stealing from clients. The detectives check the cellar and encounter the gorilla. They run upstairs, and when Jack takes a look, he sees only a cat and asks the detectives if they've been drinking. "No, but it's a good idea."
Norma distrusts Peters, but the gorilla arm emerges from a closet and turns off the light. She screams, and Jack rescues her as the gorilla scurries back into the secret passage. Peters coolly brings tea, and Jack is suspicious. The detectives tremblingly pursue the gorilla. Harrigan threatens a showdown with the gorilla, who shows up and follows him until discovered. Harrigan flees upstairs. Kitty is terrorized but the stranger advises her to stay in her room. He finds another passageway.
Jack insists the gorilla is a man in costume. The sailor comes to, insisting that the gorilla is trained but that "there's no telling" what he might do when the sailor isn't around, "especially with women; he hates women." The sailor explains to Jack that he and the ape were hired as an act for a party at the estate. The radio interrupts Norma's whimpering with an insistence that the gorilla has done his work: Walter Stevens is dead, his body in the garage. The sailor says the kitchen is a wreck and that the gorilla must be "on a rampage."
The gorilla arm from a secret passage conks Harrigan on the head and approaches Norma. Kitty is in a cage. The sailor releases her. All run into the storm to discover the ape dangling an unconscious Norma off the side of the house. The sailor gets Norma safely from the gorilla, who smashes a window and enters the house. Harrigan comes to, sees the ape, and almost faints. The sailor peacefully escorts the ape away. The stranger is discovered in the closet, and he announces that he is an investigator from the Securities and Exchange Commission. They all follow the radio's wire into another secret passage. In a hidden room is a microphone and Walter Stevens bound and gagged in a chair. Stevens protests, but is led out in handcuffs. The brusque visitor, named Conway, emerges from the closet. He too has been knocked on the head. The investigator explains that Norma was invited because Stevens would inherit. Stevens was the gorilla, which supposedly explains why no one was allowed to call the police and why the detectives hired are incompetent "morons." A hairy sleeve was what made appearances all along.
When the detectives congratulate the investigator and discover his hairy hand, they realize he was the gorilla. The man pulls a gun on them all and admits he has been the gorilla. Somehow, Stevens' involvement is explained. Peters pulls a gun on this guy from behind. Stevens calls the cops. Uncle Walter isn't a crook after all, just involved in a scheme to capture the fake gorilla doing all the murders to his firm's clients. Norma and Jack will be married tomorrow.
Commentary: The plot is too convoluted to follow and the humor is directed almost exclusively at cowardice.