Contained in the book .
Two men, Paul Dubois and Frederick Gessner are suspected of being spies against England, especially since they are close to Hartmann from the previous adventure. What they are up to, though, remains a mystery, at least until they pay a visit to a factory near the docks. With Vera's help, Ray Raymond discovers a plan to set up a wireless telegraphy system at that factory to more easily and quickly send intel to Germany.