The story involves a small town cosmetic company chemist (Lugosi) who is upset at his wealthy employers, because he feels they have denied him his due share of company success. To get revenge, he breeds giant bats. He then conditions them to kill those wearing a special shaving he has concocted. He cleverly distributes the lotion to his enemies as a “test” product. Once they have applied the lotion, the chemist then releases his Devil Bats in the night, which kill his two former partners and three members of their families. A hot shot big city reporter gets assigned by his editor to cover and help solve the murders. He (O’Brien) and his bumbling photographer (Kerr) begin to unwind the mystery with some comic sidelights. The mad chemist is, predictably, done in by his own shaving lotion, and by his own creation—the dreaded Devil Bat.
