A boy accidentally shoots a friend with a gun he found in the rubble of a destroyed building. The gun turns out to be a clue in a ten-year-old murder case. Lizabeth Scott's son, Jon Whiteley, finds a gun in a bombed out area of London and accidentally shoots a playmate. Out of fear, he flees with the gun. The bullet matches one used 10 years earlier in a murder. This brings Captain Steve Cochran into the case as well as the police, headed by Herbert Marshall. Cochran's the lead. But the criminal George Cole, who was involved years before, learns about the gun and he too sets out to find the boy and the weapon.