Salamanca, 1812.

Lord Wellington has triumphed over the French in battle, yet victory brings little peace. The Peninsular War rages on and a revelation of conspiracy threatens to shatter Britain’s fragile alliance with Spain.

Colonel Thomas Mablethorpe, an intelligence officer for the War Office, feels wasted at his current assignment as a translator. So when a summons arrives from Army Headquarters, he seizes the chance to prove his worth once more. Resourceful, discreet and quietly relentless, Mablethorpe excels at one thing above all: solving problems.

This time, however, the problem may be impossible. Someone within Wellington’s general staff is a French spy. To expose the traitor, the colonel must tread the perilous ground between three uneasy allies whilst travelling across a ravaged land scarred by years of war, where every friend might be an enemy, and every truth comes at a cost.