In the fourth book of this gripping series, the Inventory's final secrets are revealed. Having learned a troubling truth about himself in the Black Zone of the Inventory, Dev is called back into action to defend the world's greatest store of futuristic tech, and he'll need all the help he can get from his friends. Someone has stolen Winter Storm, a swarm of powerful biobots, and is using them to infect and control people! Who can be trusted now?

Hidden under a small suburban town, the Inventory is a collection of the most incredible technology the world has NEVER seen: invisible camouflage, HoverBoots, indestructible metals, and the deadly war robot Iron Fist. Dev's uncle, Charlie Parker, is the Inventory's mild-mannered curator, with security provided by Eema, a beyond-state-of-the-art artificial intelligence system. But security is catastrophically breached when Lot and Mason from school turn up unexpectedly and, hot on their heels, a ruthless gang of thieves working for the Collector and the Shadow Helix organization. If the thieves succeed in their goal to seize the Iron Fist, Dev, his friends, and the world are in a whole heap of trouble.