Mortal Engines is set in a future version of London, in which Admiral Quirke defined the principles of Municipal Darwinism and made London a moving city. After the Sixty Minutes War destroyed most of the world, Traction Cities such as London built engines that allow them to move and go hunting for smaller cities to devour. In the East, however, unmoving cities are united in the Anti-Traction League.
Fifteen-year-old orphan Tom Natsworthy is a third-class Apprentice in the Guild of Historians and works at the museum. His hero is archaeologist Thaddeus Valentine, who found many Old Tech artifacts and wrote books about his adventures. Tom meets him and his daughter Katherine while looking for relics of the devoured city and saves his life when a girl armed with a knife tries to kill him. The girl, who has a horrible scar on her face, jumps off London to escape from being captured, and Valentine pushes Tom off as well.
Tom and the girl find themselves in the mud of the Great Hunting Ground, a wasteland occupying what used to be Europe. The girl says her name is Hester Shaw and that Valentine killed her parents, because her mother refused to give him something. He also scarred Hester's face and thought he had killed her. For this reason she's now trying to kill him. In the meantime, in London, Valentine is assigned to a secret mission on board of an airship.
As Tom and Hester try to get back to London, they live many adventires. We also follow Valentine's daughter Katherine as she tries to discover why Hester Shaw wanted to kill her father.
This is a fast-paced book which kept me reading into the night. The adventures are very exciting and keep you guessing about the ending of the novel. I liked the story very much, and I think I will be reading the other books in the series. I was a bit sad about the ending, as some beloved characters encounter a sad death.