Portugal, 1809. After saving the life of Sir Arthur Wellesley, Sgt Richard Sharpe is rewarded with the field commission of lieutenant. His first mission is to go behind enemy lines to Casa Antiga to locate a missing agent, James Rothschild, who carries a banker's draft for badly needed funds for the British army. Sharpe is given command of the 95th Rifles under Capt Murray, but soon finds that they are an undisciplined bunch of louts. Neither Murray nor the men of the Rifles are prepared to accept Sharpe's command as 'proper' officers are not raised from the ranks.

Spain 1809 - Colonel Sir Henry Simmerson arrives with his new regiment, the South Essex, and Wellesley decides to keep in Simmerson's good graces by arranging for the South Essex to blow up the bridge at Valdelacasa. Aware that Simmerson is incompetent, Wellesley orders Sharpe to see that the mission is a success in exchange for a promotion to captain.