Robin Gaunt's new invention was terrifyingly, unimaginably powerful: a weapon of chemical warfare which caused "universal, instantaneous death". When Gaunt disappeared from his rooms, leaving no trace but a faint bitter smell, the police suspected that he had sold out to the other side. But Bulldog Drummond believes otherwise. Convinced of Gaunt's innocence, he can think of only one man ruthless enough to use the invention to hold the world to ransom, and he is determined to track him down before it is too lake. Then he receives an invitation to a lavish dinner-dance aboard an airship that is to mark the beginning of his final battle for triump...