Valentine finally catches up and Tom relays what the girl had said. It ends at a waste chute, where she accuses Valentine of doing something to a woman named Hester Shaw and then she jumps down the chute. An Apprentice Engineer hears Tom's cries and joins the chase. Tom prevents the murder and chases after the girl as she flees. While Tom is working with Valentine, he spies a suspicious looking girl who then tries to murder Valentine. Valentine has also brought along his beautiful daughter, Katherine. However, Tom is in luck, as the most famous London Historian, Thaddeus Valentine, is supervising the dismantling of the small town. The Historian he is working under, Chudleigh Pomeroy, discovers that Tom has shirked his duties and punishes him by assigning him Gut-duty. On the particular day that the novel starts on, he sneaks away from his duties to watch London chase a small traction town named Salthook. Due to his low status, he is picked on by Apprentices of higher classes.

Tom is a Third Class Apprentice with the Historian Guild, which is the lowest class he can be in the Historian Guild. The narration then moves to focus on one of the main characters of the novel, Tom Natsworthy. Mortal Engines begins with an introduction to the Traction City of London and its most recent history. The following version of this book was used to create the guide: Reeves, Philip.

Mortal Engines by Philip Reeve