The birds are teaching Arlo to fly…In a faraway corner of a ruined world, a mysterious boy is building a flying machine, aided in his research by birds who can talk. Then, into the extraordinary crater city of Mayda, where buildings ascend the cliffs on funicular rails, comes a refugee: a beautiful, brilliant, half-human engineer called Fever Crumb. Fever is just the engineer that Arlo needs to get his invention off the ground. But ruthless enemies stalk them, who will kill to possess their secrets – either to steal their revolutionary machine, or to destroy the secrets of flight forever. In this breathtaking story from the awesome world of Mortal Engines, Philip Reeve creates an extraordinary new landscape of moving buildings, outlandish creatures, sinister villains and groundbreaking scientific discoveries.