Synopsis: A Sing Sing inmate named Quinn (Jack Holt) is plotting an escape. His cellmate Henderson (Boris Karloff) advises against it, claiming that powerful friends will spring both of them soon if they are patient. But seeing that Quinn will not be deterred, Henderson tells him how to get in touch with his associate on the outside, a man named Arnold (Claude King).
Quinn’s escape is successful and he travels to Arnold’s mansion in the country. Arnold seems afraid to assist Quinn, but is too frightened of his employer, the mysterious drug kingpin Mr. X, to refuse. He employs Quinn as his chauffer, and Quinn becomes enamored of Arnold’s beautiful daughter Julie (Constance Cummings).
Soon enough Henderson is released and makes contact with Dr. August Steiner (Edward Van Sloan), who runs the Eastland Hospital. We learn that Steiner is also an agent of Mr. X , and he tells Henderson that Mr. X arranged for him to be incarcerated so long because he was displeased with him.
Henderson suggests Quinn as the perfect man to deliver the next drug shipment for the organization. But as soon as Steiner sees Quinn he knows the man is an undercover federal agent. Henderson is shocked and angered by this revelation.
But the plan to have Quinn to pick up the shipment via seaplane goes forward. After Quinn delivers the drugs to a ship at sea, Henderson instructs Quinn to take off and then bail out – the boat, he says, will come to his location and pick him up. Quinn, sensing that this is an attempt to dupe him, quickly “rigs a dummy”, attaches it to the parachute and tosses it overboard so that Henderson will think it’s him.
But before long Steiner captures Quinn himself. He plans on disposing of the federal agent in his usual manner – by getting him admitted to his hospital and subjecting him to an unnecessary – and fatal – operation….
Comments: After years of laboring as an extra or a walk-on in Hollywood movies, Boris Karloff won a prominent role in Howard Hawks’ 1931 drama The Criminal Code. This led to a couple of other substantial roles, including the monster in James Whale’s Frankenstein. Karloff worked on Behind the Mask after shooting on Frankenstein wrapped but before it was released. Frankenstein’s success greatly changed the trajectory of the 44-year-old actor’s career. His sudden stardom allowed the lanky Englishman to appear, improbably, as the lead in a number of films, often billed simply as “Karloff”. In the case of Behind the Mask the horror elements were played up in the promotional material, and Karloff himself was hyped far more prominently than his role warranted (in fact most of the movie posters feature a glowering Karloff, suggesting that he — and not Everett Van Sloan — is the film’s antagonist). This is a time-honored cheat that movie studios engage in — it happened to Lugosi all the time, really — and the tactic isn’t employed too egregiously here.
Of course the most infamous use of this trick was the dismal Dudley Moore comedy Best Defense (1984); hoping to cash in on the sudden stardom of comedian Eddie Murphy, who had a small role, Paramount’s marketing campaign strongly insinuated that he and Moore were co-stars. In fact the Murphy scenes were quickly shot and tacked on after the film had tested poorly with audiences, making the deception that much worse.
Karloff actually does have a fairly large role in Behind the Mask, though the character he plays, Henderson, is simply a lackey of the mysterious Dr. X. One interesting thing about the film is that it gives us a pretty clear picture of what Karloff’s career would have looked like had he never been offered a role in Frankenstein: he would have played endless variants of the Henderson character. Karloff would have been remembered — if he was remembered at all — as a character actor who specialized in underworld middle-men, gaunt crooks in cheap suits, and half-smart grifters. In the end, he ended up playing the mad scientist over and over again; but at least he was a leading man in such films.