David Mallory has designed an advanced security system that uses an optical beam which replaces the standard wired technology. He is prepared to sign a lucrative contract with Ranger Security chief Steve Ranger, with whom he has a troubled history. Mallory is betrayed by the company and his creation is shelved indefinitely, leaving him unpaid and unappreciated. Mallory’s revenge comes through a series of harmless break-ins of shops protected by the old Ranger system using his new device to bypass the alarms. He doesn’t take anything, but leaves a calling card signed “The Night Key” meant to damage the company’s reputation in the press.

Mallory goes into hiding with a small-time crook named “Petty Louie” while Ranger sends his private security force, led by the dedicated Jimmy Travers, searching for him. Travers connects with Mallory’s daughter Joan and attempts to bring her father in peacefully without charges. Things go sideways when a ruthless mobster known as “The Kid” kidnaps the inventor and forces him to participate in a series of robberies. Travers is on the case, but can he rescue the old man before things turn deadly?

Boris Karloff (Die, Monster, Die!) stars as David Mallory, a man twice screwed over by the system and now looking for a little justice. He shines in the role as a benevolent protagonist, delivering a refreshing performance far outside his familiar villainous turns. As an added bit of business, his aging character has failing eyesight and must frequently contend with the bad guys taking away his glasses to force him to do their bidding. He reluctantly agrees, primarily to protect the safety of his daughter.

Night Key is actually a pretty good movie but is in no way a horror film. It may star Karloff, but the man proved quite versatile as an actor and found much success outside the genre. That said, this picture has absolutely no business kicking off the latest installment in the Universal Horror Collection series. I applaud the effort of rescuing a forgotten title and introducing it to a wider audience, but there are plenty of more deserving genre offerings in the studio vault.