Chronically agoraphobic since the day his wife was murdered, Tommy Cowley finds himself terrorized by a gang of syringe-wielding feral children, who are intent on taking his baby daughter. Upon discovering the nightmarish truth surrounding these hooded children, he learns that to be free of his fears, he must finally face the demons of his past and enter the one place he fears the most - the abandoned tower block, known as the Citadel.

Milan, 2030: Diana Cavalieri is a double agent for the secret syndicate Citadel, who infiltrated Manticore, the rival agency that destroyed Citadel eight years ago. Trapped behind enemy lines, Diana has a chance to leave the agency forever, but she has to decide whether to trust a surprising ally: the heir of Manticore Italy, Edo Zani.