After Lady Penelope refused to invest with Warren Grafton, she let him know about another businessman interested in transportation named Jeff Tracy. Soon the automatic monotrain is taking its journey, and Jeff is also accompanied by two of his associates Brains and Tin-Tin. Grafton tries to assure them that there is no danger on the train, even showing the main automatic control unit, but Jeff and the others aren't convinced, rightly thinking that he cares more about making money than people's lives.
Later, a thundestorm strikes down one of the safety helijets that was observing the monotrain and the impact of the fallen jet destroys most of the bridge and cuts off the automatic signals, causing the monotrain to go out of control. Grafton panics and can think of no way to prevent this disaster. Jeff calls International Rescue and Brains, after several attempts, manages to slow the monotrain down.
After being saved by International Rescue, who carefully lift their carriage off the bridge and set them down safely on the ground, Jeff tells Grafton that he will be pressing charges for this act of criminal negligence. He, along with the rest of his cohorts, including Malloy and Selsdon who failed to burgle Creighton-Ward Mansion are imprisoned.