A professor teaching at a correspondence school discovers that a Nazi agent is trying to prevent a trade treaty being signed between England and South America.

An insane murderer is on the loose, and gunning for the men who put him away. Will Hay is on the list, and co-opts Claude Hulbert to try and stop…

Schoolteacher William Potts is the dual of a captured German spy, therefore he’s sent to Germany from British Intelligence to get the aims for a new secret weapon, causing turmoil…