On a Los Angeles street, Officer Rob Rawlins, John McGuire, a patrolman on his way home from work, stops a man he suspects of being a burglar and is shot and mortally wounded. The clues are sparse and don’t point to a clear suspect, leaving investigators with more questions than answers. Two detectives, Marty Brennan Scott Brady and Chuck Jones James Cardwell, are assigned to chase the killer, Roy Morgan Richard Basehart, a brilliant mystery man with no known criminal past who seems to vanish just as the net tightens.
Roy is quietly hiding in a Hollywood bungalow, listening to police calls on a custom radio in a bid to stay one step ahead of capture. His only steady companion is his small dog, a solitary existence that underscores his detachment from ordinary life. He moves cleverly, feeding stolen electronic equipment to fence Paul Reeves Whit Bissell and nearly lands himself in serious trouble when he tries to collect on the deal. Reeves, pressured by prosecutors, agrees to cooperate, hoping to turn the table on the elusive thief. The case quickly crosses paths with Brennan and Jones, who stake out Reeves’s office to arrest and question Roy, while Roy himself remains acutely aware of potential traps and advantages in every move he makes.
A brief but decisive shootout leaves Jones paralyzed and Roy wounded, forcing Roy to take drastic measures. He performs surgery on himself to remove the bullet and evade hospital treatment, knowing that confinement would quickly expose his methods and connect him to the other crimes. With a sharper understanding of police procedures, Roy adjusts his approach, elevating his crimes from burglary to armed robbery and widening the scope of danger for those pursuing him. In one robbery, investigators recover a spent cartridge, a clue that could tie a string of incidents together.
Forensics expert Lee Whitey Jack Webb helps assemble the puzzle, matching ejector marks on the recovered casing to those from the Rawlins killing and Jones’s wounding, linking all three shootings to a single, highly capable suspect. Captain Breen Roy Roberts seizes the opportunity the breakthrough provides, gathering all witnesses to the robberies and pushing the investigation forward with renewed purpose. Reeves ultimately identifies Roy from a composite sketch, a moment that tightens the dragnet even as Roy steels himself for one last gambit.
Roy’s inside knowledge of police work leads to a stalling point in the pursuit, prompting Brennan to push harder and reexamine every lead. As Brennan delves deeper, he uncovers that Morgan once worked as a civilian radio technician for a local police department before his draft into the army, a detail that explains the precision of his methods. Through patient legwork, Brennan obtains Morgan’s address via the post office and goes undercover as a milkman to surveil Roy’s apartment, testing whether the killer can be drawn out by a direct confrontation.
That night, the raid unfolds with meticulous timing, but Roy—alerted by his dog’s bark—escapes up into the attic and vanishes into the city’s storm-drainage tunnels. A tense chase follows, with a broad dragnet sweeping through the drainage system as officers hunt for any sign of him. In a final confrontation, Roy is cornered in a narrow passage where a police car’s wheel blocks his exit from a manhole. Tear gas swirls, Roy staggers, and with a last, desperate gesture he fires once more before he is fatally shot, ending a relentless pursuit that tested every resource and method the police could muster.
