Johnson is from the planet Davanna, where the inhabitants have developed an incurable blood disease, and he has been sent to Earth to examine the blood of humans for its usefulness in curing Davanna's dying race. Johnson is answerable to an authority on Davanna with whom he can communicate through a device hidden behind a sliding panel in the living room of his Griffith Park mansion. His bodyguard, Jeremy (Jonathan Haze), who also acts as his chauffeur and houseboy, provides him support and protection, but is unaware of his being an alien.