The story begins with a scientist creating a device shaped like a man that can be remote-controlled by a machine. The mechanical man possess super-human speed and strength. The scientist is killed however by a gang of criminals, led by a woman named Mado, who wish to get the instructions for building the mechanical man. The criminals are captured before they are able to get them and are brought to trial and condemned. Mado manages to escape and kidnaps the scientist's niece whom she forces to give her the instructions which she uses to build a mechanical man.

Lon Chaney performs two roles: Doctor Lamb, a mad surgeon who's doing experiments on human bodies, and his crippled and apish assistant, the result of his first experiment.

Lieutenant Commander John Byrne of the Naval Secret Service and his partner Pvt. Bill Riggers chase criminal Dr. Sin Fang, who is desperate to find a lost sacred seal. (The fifth and only surviving episode of a six-part serial about an evil mastermind inspired on Sax Rohmer's Dr. Fu Manchu.)

Dr Henry Frankenstein is obsessed with assembling a living being from parts of several exhumed corpses.

A dark and stormy night. Pluto is spirited away to the spooky mansion of an evil genius for a mad transplant scheme to put his head on the body of a chicken. Mickey gives chase, but find himself threatened severely by the house and its denizens.

An ex-vaudeville actor is working as the assistant to a doctor who has Frankenstein aspirations. The ex-vaudeville actor kills the doctor and decides to assume the identity of the dead physician.

An insane surgeon's obsession with an actress leads him to replace her wounded pianist husband's hands with the hands of a knife murderer--hands which still have the urge to throw knives.

A crazed scientist invents a serum that induces a catatonic state in whoever it is injected into. He uses the serum to paralyze his enemies, so that he can bury them alive.

A plastic surgeon goes mad when he discovers that his wife have an affair. He fakes her death and disfigure her and locks her in the cellar.

A reporter sleuths the mystery behind an oft-married Viennese doctor whose wives met mysterious fates.

A fugitive doctor (Lionel Atwill) tries to raise the dead for South Sea Islanders.

Dr. Alfred Morris, a university chemistry professor, rediscovers an ancient Mayan formula for a gas which turns men into pliant, obedient, zombie-like ghouls. After medical student Ted Allison becomes a guinea pig for Morris, the professor imagines that Allison's fiancée, a beautiful concert singer Isabel Lewis, wants to break off the engagement because she prefers the professor as a more "mature" lover but in reality loves Eric, her accompanist. In order to bring Ted back from his trance-like states, Morris commands him to perform a cardiectomy on recently deceased or living bodies in order to use serum from their hearts as a temporary antidote. When the serial murders seem to coincide with Isabel's touring schedule, ace reporter "Scoop" McClure gets on the mad scientist's trail.

A mad doctor (Bela Lugosi) and his helpers (John Carradine, George Zucco) lure girls to his lab for brain work, to help his wife.

An eccentric scientist helps a fugitive from the law become invisible, unwittingly giving him the power to exact revenge on his former friends.

Once again Paula the ape woman is brought back to life, this time by a mad doctor and his disfigured assistant, who also kidnaps a nurse in order to have a female blood donor.

A scientist working on cures for rare afflictions, such as a bone softening agent made from molds to allow him to correct the spinal deformity of his nurse, finds the physical causes of lycanthropy in wolf-man Larry Talbot and of vampirism in Count Dracula, but himself becomes afflicted with homicidal madness while exchanging blood with Dracula.

John Carradine stars as Dr. Charles Randolph, a scientist dedicated to deciphering the secrets of life and death. Aided by assistant David Cochran (Robert Shayne), Charles conducts experiments that have horrifying side effects. Charles's lonely wife, Elaine (Claudia Drake), is frightened by his work, and in order to protect her, housekeeper Maria (Rosa Rey) unleashes a torrent of voodoo that wrecks havoc.

In this thriller, psychiatrist Dr. Cross (Vincent Price) kills his wife and expects to get away with murder, until he discovers that the slaying was observed by a next-door neighbor, Janet Stewart (Anabel Shaw). As Janet attempts to convince her husband (Frank Latimore) of the doctor's dastardly deed, Cross shows up to advise him that Janet is in dire need of some in-depth counseling.

A scientist takes a the brain of dead man and revives it via electrodes as it lays suspended in a tank of liquid. Soon, the brain grows to possess enormous psychic powers and inflicts its personality upon the doctor who saved creating a "Jekyll and Hyde" paradigm.

Murders, with victims dying from spines broken by brute strength, erupt in the city and the killers, when encountered, walk away unharmed by police bullets which strike them. A police doctor's investigation of the deaths leads to the discovery of an army of dead criminal musclemen restored to life, remotely controlled by a vengeful former crime boss and a former Nazi scientist, from the latter's laboratory hidden in the suburbs.