While lost near the Spanish-Portuguese border, Sharpe and his company surprise a group of French soldiers in unusual grey uniforms, caught in the act of raping a teenage Spanish villager.

Back at headquarters, Sharpe is informed by Major Michael Hogan that the Real Compania Irlandesa, the royal bodyguard of the captive King of Spain, have been sent to join Wellesley's forces.

There Sharpe also has to deal with former Wagon Master-General Colonel Claude Runciman, a grossly fat and indolent man.

Pierre Ducos, a French intelligence officer answering to Napoleon himself, has planted an agent within the Compania Irlandesa, Dona Juanita de Elia, a Spanish noblewoman, the mistress both of the unit's commander, Lord Kiely, and of Loup.

That night, Loup attacks the fort, massacres the Portuguese, and is only driven off when Sharpe's friend, Tom Garrard, sacrifices himself to blow up the ammunition wagons.

To avoid this, Sharpe attacks Loup's hideout but finds it deserted, except for Dona Juanita, who is exposed as the enemy agent, and courier of the forged newspapers.

The French, led by Marshal André Masséna, prepare to cut the British off from their only route of retreat and bring Wellesley to battle.

The plot remains largely the same with regard to the French circulating newspapers describing imaginary massacres in Ireland by British troops in the hope that Irish soldiers will desert.