When landlord Semple Ridgedon finds a society of murderers lodging in one of his buildings, he tears the place down and rebuilds it in a modern way. But the evil ghosts appear anew and confront Ridgedon with his promise to join them in their cult of murder.
Ghost hunter Bruce Gibson buys a haunted house and challenges a satanic "dark stranger" to work his worst magic. He conjures a "monster's ghost" out of the bodies of four dead men, a black bull and drops of Gibson's blood. With the help of this powerful demon the dark stranger matches his wits against the ghost hunter's.
Eric Barnes, an audio engineer, is captured by sinister count Pramevi (anagram for 'vampire'). He is to build a recording machine to preserve the count's voice for all eternity. But Barnes constructs a supersonic weapon that disturbs the vampire's flight. Pramevi crashes to the ground.