Tom has finally perfected one of his latest inventions, a noiseless airship.

This is a project Tom has been working on since the last few volumes, and now that it is finished, it appears that Tom is suddenly under scrutiny by United States border agents, who are tracking smuggling operations which utilize airships to move goods out of Canada, and avoid paying duty tax.

Once Tom convinces the agents that he is not involved in smuggling, he is hired to help break up the operations.

In previous volumes, but only mentioned peripherally, Tom has been working on a noiseless airship.

Built for use in this adventure is Tom's giant searchlight, as the title of the story suggests.