Lloyd Bridges plays an ex-GI, Frank Pryor, who arrives in London to visit a wartime girlfriend, whom he hasn’t seen in six years. His arrival at the airport coincides with a man being killed by a sniper, and he finds himself to be a suspect. Pryor is detained by Scotland Yard for questioning. Released, he goes to his girlfriend’s apartment, and learns that she had an intimate association with the slain man. Scotland Yard keeps a watch on the couple while Frank tries to unravel the mystery of the “limping man”.