As the fifth novel in acclaimed historian Adrian Goldsworthy's Napoleonic series opens, British fortunes in the Peninsular War are at their lowest ebb. Lieutenant Hamish Williams of the 106th Foot will soon discover just how precarious their situation is, and what bloody sacrifices are necessary to prevent total victory for the French.
While the Navy keeps the British foothold at Cadiz from falling to the enemy, help from the valiant but divided Spanish guerrillos will be vital if the French advance on land is to be halted. Alongside the experienced 'exploring officer' Lieutenant Hanley, Williams joins the Spanish partisans behind enemy lines, but while he learns much about the viciousness of guerrilla warfare - not least that women can sometimes fight with all the ferocity of their male counterparts - he quickly finds that the greatest danger comes from his own side.
Carrying vital knowledge of a traitor, Williams must find his way back to the British lines before a deadly French trap can be sprung, but with the British commanders determined to go on the attack, will he be able to avert disaster?