Summer 2011.  Richard Mariner and his daughter, Mary, are escaping the gathering London Olympic fever by visiting the Maritime Museum at Chatham when they get caught up in a terrorist attach and are lucky to escape with their lives.  Among the survivors is a man who turns out to be one of the terrorists, Sayed Mohammed, and he is quickly arrested.

Subsequently, Richard becomes involved with fitting out a new prison ship, Discovery, moored in the estuary of the River Thames.  This is part of a new government initiative which will see the ship filled with the most dangerous Islamic extremists in the country – one of whom is Sayed Mohammed.

As the 2012 Olympics draw ever nearer and the case against Mohammed progresses, Richard and Mary learn more about the terrorist and the prison ship.  Soon they uncover and terrifying plot, and Richard realizes he is the only man who can save the capital from certain destruction.