Inspector Willoughby is in Paris looking to capture the famous international spy, Agent X-13. He finds the spy "disguised" (with his head upside down) but Willoughby uncovers the "disguise" and gives chase. Agent X-13 ends up at the train station and riding the Orient Express. The Inspector follows with the agent using a variety of schemes to do away with Willoughby. He notices a downhill grade and sends a safe sliding down to crush the Inspector but the grade becomes an uphill grade and the safe ends up crashing into X-13. X-13 tries feeding him several poisonous foods and Willoughby's stomach turns out to have a trap door. Finally, Willoughby and X-13 battle on top of the train with X-13 leaping from the train to avoid hitting a tunnel and lands in Willoughby's net, then finding himself tied to a scale after going through the tunnel. The Inspector, having captured the crook, exclaims, "That's what I call apprehending crime on a big scale!"