James Ivan Murray is a name known to most police. When he suddenly turns up in Matlock to work as a strapper at a racing stable, Det. Sgt. Maddern is not terribly happy. Murray's major profession is that of a safe cracker, and Maddern is not satisfied with Murray's innocent attitude toward a robbery and bashing in Melbourne. When three youths attempt to blow open a bank with a land mine, the attempt goes wrong and one of them is trapped with an unexploded mine nearby. Murray is enlisted to defuse the mine.