Its existence is no more than a rumour - a ghost force unbound by rules. Deniable, and devastatingly effective, MI6's Spartan Section is the West's last line of defence. And super-spy Will Cochrane is their most prized asset - and deadliest weapon.

'He has betrayed us and wants to go to war.' That was the cryptic message received by the CIA from an agent operating deep undercover in Russia. Unable to make contact, the Director of Operations is forced to turn to one of his most deadly field officers: Will Cochrane. His mission: track down the agent and decode the message - or die trying. Will successfully locates the agent, but finds him near death, his last words: 'Only Sentinel can stop him.' Now it's up to Will, with the help of the top-secret joint CIA-MI6 Spartan Section, to discover the identity of the legendary operative known...

Will Cochrane monitors the nighttime streets of Gdansk, Poland, waiting for the appearance of a Russian defector, a man bearing a top-secret document. Will believes the defector is about to step out of the cold and into the hands of Polish authorities, but suddenly everything goes sideways. The target shows up, but so does a team from the Russian foreign intelligence service SVR, and they are hell-bent on keeping the man from walking. Then, in a hail of crossfire, a van speeds into the melee and snatches the defector out from under them all. Everyone wants the man and the codes he carries -...