London. Two powerful crime families, the Harrigans and the Stevensons, are engaged in a war for power, avoiding direct confrontation. But the shaky truce may be broken by the disappearance of Tommy, the son of the head of the Stevenson clan, who was last seen in a nightclub with Eddie Harrigan. The head of the Harrigan clan assigns Harry De Sousa, an experienced "problem solver," to handle the situation.