From the blurb:

'You're going up the Valley'

Lieutenant Black doesn't even know its proper name. But he knows about the Valley: it's the farthest, the hardest and the worst.

You have to travel far beyond the other remote outposts, deep into a maze of interlinked mountain passes, just to get to its mouth. Stories circulate periodically, but they are impossible to verify. Everything about the Valley is myth and rumour.

That Black has been sent there to investigate a warning shot fired by a near-forgotten platoon – the final bureaucratic insult in his short and unhappy army career. But as he starts to unearth the dark secrets of the strung-out soldiers besieged within Combat Outpost Vega, Black will find himself drawn into an obsessive odyssey of discovery that will threaten not only his life, but also the lives of everyone else in the Valley.

Left on the bookshelf.