For many, Haynes, known as "Gunner", is not an outlaw but a gentleman of unorthodox methods. For Scotland Yard, he is one of the most skilled thieves in the world. The Gunner and Luke Maddison belong to completely different worlds; Luke is a respectable banker with a charming girlfriend, Margaret Leferre. But Luke has done a favor for the "Gunner" that he'll never forget, so that when the banker gets in trouble, the Gunner intervenes to get him out of his nightmare...