Following the US execution of Bin Laden, a Syrian sleeper cell detonates a nuclear bomb in the heart of London by ramming a vehicle into the Bank of England. Forced to take shelter from the packed radiation dust, a seemingly random group of people gathers in a hairdressing salon nearby. They are all connected to the attack in some way, but how? It is up to MI5 agent Tony Underwood to prevent the bombers' next attack and crack the secrets that everyone is trying to hide from him.