Karloff stars as a good guy for once in this fun, low-budget thriller. He plays an aged, nearly blind scientist who is robbed of his burglar alarm invention by his evil partner, Hinds, who owns a security company. Though ill, Karloff decides to invent a superior burglar alarm to provide
for his daughter, Rogers, after his death. Karloff sells the new alarm to Hinds' company for royalties, but Hinds refuses to sell the device. Seeking to force Hinds to live up to their agreement, Karloff invents an apparatus that nullifies the old burglar alarms. At night he uses his device to
gain entry into stores protected by Hinds' old alarms. Knowing he'll be ruined if this con...