Pyrennees, September 1813
Lost in the Spanish hills, Sharpe's men come across the attacked remains of an English wagon train and then the sacked village of Casa Antiga. They find out that both were attacked by the Wolf Brigade, named after their commander, Brig. Gen. Guy Loup. Meanwhile, Wellington has been given the Royal Irish Company, led by their colonel, Lord Kiely, the palace guard of King Ferdinand VII of Spain. They are raw troops and of little use, so Wellington posts them next to the French lines and tasks Sharpe with knocking them into shape. He believes they will desert, and the sooner the better.
Sharpe starts to teach them how to fight, and sure enough, the desertion starts. Intent on retrieving some ammunition captured by Loup from the wagon train, Sharpe and Kiely go to the town where Loup is based. They are attacked, losing many men. They also find the bodies of their deserters that have been butchered by Loup.
Lord Kiely invites Sharpe to dinner. Also at the table are Kiely's wife and a Spanish partisan, Dona Juanita, who is Kiely's lover. After the dinner, Lady Kiely begs Sharpe to persuade her husband to end the affair.
Loup attacks at night and a fearsome battle ensues. The Irish Company fights him off, and Sharpe wants to follow through with a counter-attack. Lady Kiely reveals to her husband that she is pregnant and he sends her home to safety. Instead, she is captured by Loup. Sharpe attacks Loup's town, but they ready for him. He has been betrayed.