On the mystic island of Lemuria, the cult of Ubasti seek the Egyptian Princess Nadji to sacrifice so that their goddess Ossana, whose soul resides in Nadji's body, may be resurrected by Black Magic. Nadji is located in the Far East port of Suva, but shielded by the White Magical powers of Frank Chandler, an American raised by Eastern mystics who is also known as Chandu. When Chandu takes a voyage alone, however, the evil Voice of Ubasti is able to magically spirit her to Lemuria, where Black Magic reigns supreme. Chandu sets out in pursuit with his sister Dorothy, niece Betty and nephew Bob; but, shipwrecked on the magic island, Chandu finds his family also held prisoner for sacrifice while he is plunged into an endless maze of caverns beneath the evil temple, where both his mortal and magical strength seem rendered useless.

Wealthy Jack bets friend Michael he can woo Lu Lu without money within 2 weeks. Michael hires inept detectives to stop Jack, leading to comedic misadventures as Jack pursues Lu Lu while hiding his penniless state.

Although his murdered friend was by all accounts a scoundrel, Edward Wales is determined to trap his killer by staging a seance using a famous medium. Many of the 13 seance participants had a reason and a means to kill, and one of them uses the cover of darkness to kill again. When someone close to the medium is suspected she turns detective, in the hope of uncovering the true murderer.

In 19th century England, a noted brain surgeon rescues a former student from being hanged on a false conviction for murder, and spirits him away to an ancient, repurposed abbey far in the countryside. There, he connives his pupil into assisting him in mapping the functions of the various parts of the human brain, using living subjects who are under a terrible animation-suspending drug called "black sleep". Subsequently, the student, along with the daughter of one of the subjects, discover that most of these subjects have survived but are being kept in a dungeon-like cellar, in various stages of physical and mental derangement...

Two actors who play detectives on the radio find themselves investigating a real crime masterminded by an arch-criminal named the Cobra.

The entertainment duo Mitchell & Petrillo, en route to a USO show for troops in Guam, fall out of their plane and end up on the jungle island of Cola Cola, where the mad scientist Dr. Zabor is conducting evolutionary experiments.

An insurance salesman, Albert Tuttle, is hired as a body guard for a millionaire.

In 1918, an English family is terrorized by a vampire, until they learn how to deal with it. They think their troubles are over, but German bombs in WWII free the monster. He reclaims the soul of his wolfman ex-servant, and assuming the identity of a scientist who has just escaped from a concentration camp, he starts out on a plan to get revenge upon the family.

Insurance agent-physician collects on policies of men murdered by a disfigured resident of the home for the blind where he acts as doctor-on-call.

The East Side Kids try to fix up a house for newlyweds, but find the place next door "haunted" by mysterious men.

A group of delinquents on their way to summer camp get stuck in a haunted house.

A woman is married to the son of a doctor, the proprietor of a private sanatorium, where she is under unwilling treatment. Both the son and the doctor indicate they want the marriage dissolved. Arriving at the scene is a mysterious personage identified as the doctor's cousin who formerly was a stage magician in Europe. He is accompanied by a threatening dwarf.

The heirs to a family fortune are required to attend a seance at the spooky old family mansion. However, throughout the night members of the family are being killed off one by one.

The town's leading citizen becomes a homicidal maniac after his wife deserts him.

A seemingly charitable soup kitchen operator (who moonlights as a criminology professor) uses his Bowery mission as a front for his criminal gang. Police attempt to close in on the gang as they commit a series of robberies, murders and bizarre experiments on corpses.

After several female motorists begin disappearing en route to Twin Falls, a Hollywood screenwriter and the cousin of his bride-to-be discover that they've all been abducted by the mysterious Dr. Marlowe, who is attempting to resurrect his dead wife.

Dr. Paul Carruthers is frustrated because he thinks his employers, Mary Heath and Henry Morton, have cheated him out of the company's profits. He decides to get revenge by altering bats to grow twice their normal size and training them to attack when they smell a perfume of his own making. He mixes the perfume into a lotion, which he offers as a gift to Mary and Henry. When they turn up dead, a newspaper reporter decides to investigate.