When German Intelligence discovers that Winston Churchill will meet with President Roosevelt to plan the invasion of Europe, it activates its prized asset in London. Martin Rikaard, a sleeper agent, devises an operation to penetrate the Queen Mary and signal its location to a waiting U-boat pack. Only one man believes such a mission is feasible: Daniel Gale, a Scotland Yard detective whose suspicions that a routine death is the work of an assassin lead him onto Rikaard's trail. Opposed by a quarry always one step ahead of him, Gale spearheads a nationwide manhunt that climaxes on the vulnerable liner as it races through the submarine-infested waters of the North Atlantic.
