Mortal Engines is a movie based on a novel by Philip Reeve, set in a post-apocalyptic world where cities are mobile and compete for resources. The story follows Hester Shaw, a young woman who seeks revenge on Thaddeus Valentine, a powerful engineer who killed her mother and plans to use a superweapon to destroy the static settlements of Asia. Along the way, she meets Tom Natsworthy, a historian who learns the truth about Valentine's scheme and joins her in stopping him. They also face Shrike, an undead cyborg who raised Hester and wants to turn her into one of his kind.