An alien from the planet Davanna (Paul Birch) appears human and lives in Los Angeles under the name of Mr. Johnson. The only clues to his extraterrestrial nature are his sensitivity to high-decibel sound, his stilted and formal way of speaking, and his blank, white-eyed stare, which he hides with sunglasses. Otherwise, he could burn through people’s eyes into their brains. In an aluminum attaché case, he keeps his equipment for removing the blood of his victims. His first such is a teenaged girl.

On Davanna, an incurable blood disease is raging, and he has been sent to Earth to study the blood of humans. He communicates with the authorities back home with a device behind a hidden panel in the wall of his gorgeous mansion in Griffith Park. His bodyguard, chauffeur, and houseboy Jeremy (Jonathan Haze) helps him but does not know he is an alien.

He hires a nurse named Nadine (Beverly Garland) to look after him. Her boss, Doctor F.W. Rochelle (William Roerick) is under Johnson’s hypnotic control. Since there is a limit on the number of transfusions he can be given, he has to murder people and drain their blood. The police are mystified by these vampire killings—a Chinese American man walking by, a door-to-door vacuum cleaner salesman, and a trio of homeless alcoholics.

A telepathic female from Davanna (Anna Lee Carroll) turns up, who needs an immediate transfusion. He helps by stealing blood from Doctor Rochelle’s office, but he steals blood infected with rabies. The woman from Davanna collapses in the street and dies in the hospital. Officer Harry Sherbourne (Morgan Jones) tries to question Doctor Rochelle, but he is under hypnotic compulsion. Frightened now, Johnson sends an oxygen-activated umbrella-like flying creature (don’t ask) to kill Rochelle. He also kills Jeremy, who has noticed strange things in the mansion.

He tries to kidnap Nadine, but she manages to call the Police as he pursues her with his car. The police threaten, he abandons Nadine and flees. As he is pursued by Sherbourne on his motorcycle, the siren causes him to crash his car, and he dies. After the funeral, a man wearing dark glasses and carrying a metal attaché case appears.

The movie was produced and directed by Roger Corman for his Los Altos Productions, written by Charles B. Griffith and Mark Hanna. It was released in the U.S. in a double feature with Attack of the Crab Monsters, for the drive-in. It made a 400% profit in the first week. It was called a minor gem by some reviewers, with imagination, good humor, and sheer joy in film-making—rather like Ed Wood’s movies. It was remade in 1988 with Traci Lords, and in 1995 with Michael York.

Paul Birch, after an argument with Roger Corman, walked off the set and his remaining scenes were shot with Lyle Latell. Good thing the character wore dark glasses. One of the alcoholic homeless people was played by Hank Mann of the original Keystone Kops. He had been in movies for 45 years. Someone forgot to print the copyright year on the film, and it immediately fell into the public domain. For its TV remake in 1963, a prologue was added, and some scenes were repeated to bring it up to 71 minutes.