In the 7th of Columbia's "Whistler" series, truck-firm owner Steve Reynolds gets involved in a feud with a rival firm, and shortly thereafter is slugged by a masked assailant who steals the truck he is driving. The assailant runs down a policeman in the truck and leaves other clues pointing to Reynolds as the cop killer. With only a glove, with diamonds stuck in the thumb, as a clue, and while evading the police and other characters after him and the diamonds, Reynolds finally runs down the guilty party and clears himself.