The Devil’s Engine is a machine from the darkest parts of history. It can make any wish come true—as long as you are willing to put your life on the line. When a sixteen-year-old asthmatic kid named Marlow Green finds himself trapped in a surreal firefight against nightmarish creatures in the middle of his New York City neighborhood, he discovers a squad of secret soldiers dedicated to battling the legions of the Devil himself. Faced with monstrous apparitions, ancient weaponry, and his own hellishly tedious high school existence, Marlow submits to a demonic deal with the infernal device that enables him to join the battle—if it doesn’t kill him first.

Thrown into a relentless war against the forces of darkness, fifteen-year-old Marlow Green and his squad of secret soldiers must fight for control of the Devil’s Engines―ancient, infernal machines that can make any wish come true, as long as you are willing to put your life on the line. But after a monstrous betrayal, Marlow, Pan and the other Hellraisers find themselves on the run from an enemy with horrific powers and limitless resources―an enemy that wants them dead at all costs. Failure doesn’t just mean a fate worse than death for Marlow, it means the total annihilation of the world. And when all looks lost and the stakes couldn’t be higher, just how far is he willing to go?

In the third and final book of Alexander Gordon Smith's Devil's Engine series, Marlow and Pan are in hell. Literally in hell. Faced with the awful truth of being trapped in the underworld for an eternity―of Pan being trapped―Marlow makes a final deal with the Devil, a deal to go home. But he should have known: there is no real escape from a fight with the ultimate enemy. And when all hell breaks loose, it will be a war to end all wars―with demonic creatures spilling into the streets, monsters emerging from the shadows. Only the Hellraisers stand in their way, and they're not sure this is a battle they can win. They have no powers, they have no weapons. But they have each other, and they have hope, and they know how to kick ass.