This is the remarkable story of what were known by the British as 'Q' Ships and by the Germans as 'Decoy Raiders'. Disguised as harmless merchant ships, they could be transformed in moments into powerful killers and were used by both sides in the First World War. The book describes the extraordinary lengths that both sides went to ensure secrecy and deception.

Voyages often lasted several years without returning to port. Owing to the nature of the game, evidence regarding their work is hard to come by but Tony Bridgland has produced a fascinating piece of detective history.