In the Hannover Game, Byford is once again drawn back into service with Hannover, the secretive organisation he left several years earlier. The promise of a reward close to home proving impossible for the ageing operative to refuse. Meanwhile the Anti-Subversion and Terrorism Unit (ASTU) move into action to investigate a bold terrorist attack. Nelson and his protégé Melissa lead the investigation for ASTU, but what should be an exemplary investigation soon runs into difficulties and dangers.
While ASTU hunt the perpetrators of the crime, the investigation and the attack become a game of opportunity for more than one side. In the world of Hannover everything and everyone is connected, no one will leave the Hannover Game untouched.