As the film opens, a man, Frank Johnson (Ross Elliott), is walking his dog in the city at night. He witnesses a man in a car talking about a crime. The man then gets shot. But whoever shot that man then sees Frank and shoots at him. The shot misses, however, because it is mistakenly aimed at Frank's shadow. The killer then flees in the car.

When the police arrive it is explained that the shooting victim was going to testify in a court case against a gangster. Since Frank saw the shooter, the cops now want Frank to testify...