The South Essex Regiment is in need of recruits so Nairn grants Sharpe permission to return to England to find if the regiment's second battalion has the men needed. Sharpe heads to the battalion headquarters with Harper, D'Alembord and Price and finds only a few wounded men but is told battalion recruiting parties have been seen, yet no-one knows where the recruits go.
Sharpe is then summoned before the Prince Regent where he meets Lord Simon Fenner, the secretary of state for war. Fenner has his mistress, Lady Anne Comoynes, seduce Sharpe to find out what he knows, and then sends two soldiers to kill him. Sharpe kills the two assassins and Sharpe's friend Maggie Joyce makes it look as though the bodies are them. They then join a South Essex recruiting partner under assumed names. They are taken to a secret and brutal training camp in Foulness, run by the second battalion's commanding officer Lieutenant-Colonel Girdwood and the regiment's disgraced founder Sir Henry Simmerson. Sharpe learns that Fenner, Simmerson and Girdwood are illegally selling the recruits to other regiments after training them.
Harper is sentenced to be hunted to death after he tries to prevent a would-be deserter being killed in cold blood. Sharpe rescues him and, with help from Simmerson's niece Jane Gibbons, they escape to London. Sharpe reports his findings to his former commander Sir William Lawford but Lawford tries to do a deal with Fenner which will see the matter covered up and Sharpe paid off with command of a regiment in the American wars. Lady Anne, who has been forced to prostitute herself to Fenner to pay off her late husband's debts, informs Sharpe. Sharpe and his friends take charge of the training camp from Girdwood but are unable to find evidence of the illegal sales. Instead, Sharpe takes the second battalion to London and presents them to the Prince Regent at Hyde Park, proving they exist.
Fenner and Simmerson attempt to have Sharpe court-martialled but are foiled when Lady Anne arrives, having found the incriminating ledgers. Fenner is forced to cancel Lady Anne's debts and give in to Sharpe's demands: A proper second battalion and training camp will be set up, while Sharpe will take the recruited soldiers, including Girdwood, back to Spain with him. He also takes Jane and marries her. At the Battle of the Nivelle, Girdwood is driven mad by his first taste of battle, leaving Sharpe in command until a new colonel is appointed.