Sleeper 13

Smuggled to the Middle East as a child. Trained as one of the most elite insurgents of his generation. Forced to do things no one should, for a cause he couldn't believe in. But as his brothers were preparing to kill, he was looking for a way out. Now, on the eve of the deadliest coordinated attacks the world has ever seen, he'll finally get his chance. He will break free and hunt down those who made him a monster. He must draw on all his training to survive. He is Sleeper 13.

Aydin Torkal - aka Sleeper 13 - is on the run. Hunted not only by the world's intelligence agencies but also by the elite brotherhood of insurgents he betrayed, he has lived the past year like a ghost. Until now. MI6 agent Rachel Cox knows Aydin better than anyone. The only person who believes he is an ally in the ongoing war on terror, not the enemy. So when a coded message arrives from him, warning her not to trust her own colleagues, Rachel must choose between her career and the truth. 

Against all odds, Aydin Torkal - aka Sleeper 13 - broke free from the terrorist group that took him as a child and raised him into a life of violence and hate. In the two years since, he's been tracking and killing all those responsible. But he's not done yet. Now living a secret life in London, he receives a surprise visit from Rachel Cox of MI6. She needs his help to infiltrate a sinister new terrorist cell who've taken root in the USA. Aydin is initially reluctant.