When a reporter is killed under mysterious circumstances, the political cartoonist on his paper begins to investigate on his own. He finds that a vengeful industrialist may be trying to manipulate an international peace conference to stage a bombing attack on London.
A husband-and-wife detective team look into the murder of one of her friends, whose father--a prominent scientist--has been kidnapped. They find themselves up against a sinister crime organization headed by a mysterious figure known only as "Z".