A Los Angeles-based Spencer Tracy plays Joe Graham, a calm and capable telephone line repairman who prefers the steady reward of solving problems on the job to chasing a quick promotion. The film opens with a moment of choice: an upgrade offer lands on his desk, but he declines, affirming that his true calling lies in being a steadfast “trouble shooter” out in the field, where every line and circuit tells a story of how people connect.
When Joe’s partner Dan Sutter cannot work the night shift, a new repairman named Casey, Jack Oakie, steps in, bringing with him a reputation for practical jokes and a restless energy that unsettles the routine. The shift soon grows strange: the two men stumble into a series of odd occurrences, culminating in the discovery of a corpse at the site of their very first assignment together.
After their shift, the pair heads for a drink and encounters Dan in a casino, profoundly intoxicated. As the night unfolds, Casey overhears that a raid by the authorities is incoming and uses this information to warn his colleagues and the casino owner, turning the raid into a near-miss and leaving everyone involved unsettled. The next day, the aftermath lands squarely on Joe and Casey: they’re accused of tipping off the casino and inadvertently ensuring the raid’s failure. In an effort to clear his name, Joe explains the sequence of events to his supervisor, including Dan’s recent visit to the casino; the consequence is a swift firing for Dan, who loses his job without notice.
Meanwhile, Joe’s complicated love life with Ethel Greenwood, Constance Cummings, oscillates between reconciliation and strain. They had parted when Joe suspected her ofDating Dan while he was working overtime, only to reconnect later. Yet the renewal of their relationship coincides with Dan’s own misdeeds and the fallout from the casino raid, and Ethel’s trust in Joe wavers anew. The tension between personal loyalty and the murky world of crime thickens the air around them.
Soon, Joe learns that Ethel’s new work scenario involves an office that doubles as a cover for a racketeering operation run by two men: George and Max. The operation hinges on tapping into the phone lines of a nearby investment company to harvest secret stock tips, a scheme that closes the circle between crime and corporate deception. The men behind the scheme—the ruthless figures at the helm—include George Irving as Parsons and Joe Sawyer as Max, whose roles loom large as the investigation unfolds.
Unaware of the deeper underbelly until they are sent to examine the investment company’s lines, Joe and Casey uncover the tap and disrupt the operation, only to find Dan on the verge of a more dangerous betrayal—trying to penetrate the company’s vaults. They are captured and bound by the criminals, but Joe’s quick thinking comes to the fore: he uses a pocket knife to short the electric line to the local fire station, briefly triggering help that is frustrated when the first responding crew departs after finding no smoke. In a second attempt, Casey tips over a can of kerosene and a lamp, starting a blaze that forces a dramatic, second arrival of the firemen. They rescue Joe and Casey, but the ordeal leaves them seriously burned and hospitalized.
Dan, however, manages to escape the immediate scene. Joe, ever determined, alerts the police and heads to Dan’s apartment with Casey, only to discover that Ethel has arrived in pursuit of Dan’s plans for a Mexico-bound escape with the bounty. The scene ends in tragedy: Dan is found shot dead, a torn check clutched in Ethel’s hands and her fingerprints on it, leading to her arrest for murder and for involvement in the racketeering operation.
Despite the mounting evidence, Joe doubts Ethel’s guilt and resolves to uncover the truth. His quest leads him to Pearl Latour, Judith Wood, a suspect who finally confesses during their search in Long Beach. Pearl admits she killed Dan to protect her own stake in the money, a sum she believed Dan intended to sign over to Ethel. Fate takes a dramatic turn when the Long Beach earthquake of 1933 shakes the coast, forcing Joe and Pearl to flee as the house collapses behind them. They manage to connect Pearl’s confession to the Los Angeles Chief of Police via an emergency line, a moment captured on a dictaphone that secures the resolution of the case and clears Ethel.
In the aftermath, Ethel is released, and the film closes with a social turn toward happiness and new beginnings. Joe and Ethel are among the guests at Casey’s wedding to Maizie Bryan, Arline Judge, at city hall, where Ethel gently nudges Joe toward securing a marriage license of his own. The story lingers on the idea that love and loyalty can survive a labyrinth of crime, deceit, and danger, even as the city around them continues to hum with electric lines, whispered schemes, and the tremors of a city trying to keep pace with a changing world.
