For Valour: Andy McNab's best-selling series of Nick Stone thrillers - now available in the US

When a young trooper is shot at the Regiment's renowned Killing House at the SAS's base in Hereford, Nick Stone is perfectly qualified to investigate the mysterious circumstances more deeply.

But less than forty-eight hours later, a second death catapults him back into the firing line - into the telescopic sights of an unknown assassin bent on protecting a secret that could strike at the heart of the establishment that Stone has, in his maverick fashion, spent most of his life fighting to protect.

And now that the clock is ticking, Stone hurtles from the solitude of a remote Welsh confessional to Glencoe - whose shadows still whisper of murder and betrayal - and on to southern Spain, in an increasingly desperate quest to uncover the truth about a chain of events that began in the darkness of an Afghan hillside, and left a young man haunted by the never-ending screams of a friend the Taliban skinned alive.

Nick Stone's most heart-stopping adventure yet will force the reader to recognize the thinness of the line that separates sacrifice from suicide, to share the nightmares that walk hand in hand with heroism and to count the real cost of actions taken in the name of loyalty.