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...