Into a world armed to the teeth there suddenly comes a strange gospel of disarmament. Briefed to investigate the intrigue is Sidney Boyd of MI5, and from a murdered diplomat his adventures take him to the fantastic Earth Two, an exact duplicate of our own planet in so far as living beings are concerned, and it falls to him-with the help of Orwena Exburg of Earth Two-to try and smash the deadly plan which is being matured against the peaceful nations of the world. Boyd and Orwena solve the mystery of Earth Two after making a landing on the moon and discovering something about it never before suspected by Earth scientists...