Mad scientist Dr. Paul Carruthers (Bela Lugosi), creates a giant murderous bat by inundating a normal bat with electrical current. He plans to seek vengeance on his employers, the Heath family, whose cosmetic firm has generated many millions of dollars through sales of the shaving lotion that the doctor had created. Although he had willingly sold the patent rights to the family, he begins to systematically murder them with the monstrous flying demon he has bred. Asking his victims to sample his latest shaving lotion, he admonishes them to apply a bit to "the tender part of the neck." Unfortunately for them, the hideous devil-bat has been taught to attack that particular scent with predictably lethal results. Forebodings of Carruther's malevolent intentions are signaled in his sinister accent as he warmly bids them "Goodbye."
