Richard Sharpe is a scrappy Sergeant with the second Battalion of the 95th Rifles. After bravely saving the life of the Sir Arthur Wellesley (the future Duke of Wellington), Sharpe is rewarded with a field commission, making him a lieutenant. In command of the 95th Rifles under Captain Murray, Sharpe soon finds that they are an undisciplined bunch. Neither Murray nor the men of the Rifles are prepared to accept Sharpe's command, because ‘proper’ officers are not raised from the ranks. His first mission is to go behind enemy lines to locate James Rothschild, an agent missing in Casa Antiga, with badly-needed funds for the British army. Sharpe has his first encounter with Commandante Teresa and Major Don Blas Vivar, on watch in the hills when Sharpe’s company is attacked. All except Sharpe and a small band of Chosen Men are killed. Sharpe continues with the mission he has been given, and Teresa and Blas Vivar agree to go with Sharpe to Casa Antiga if Sharpe will accompany them on their own mission to Torrecastro afterwards. When they find Casa Antiga, it has been attacked by the French under Colonel de l'Eclin, but there is no sign of Rothschild. Left behind are a Methodist couple, Mr. and Mrs. Parker and their daughter Louisa. The family are taken into Sharpe's protection. Sharpe discovers his real mission is to escort one of Spain’s holiest relics, an ancient flag, and he doesn't wish to continue to Torrecastro. But Vivar's request is reinforced by the appearance of Maj. Hogan, Wellington's 'exploring officer'. Sharpe is ordered to hold the town while the relic of St. James is flown to inspire the Spanish to rise up against the French.

Sir Arthur Wellesley takes the army into Spain. In camp, Sharpe and Harper watch the arrival of a new regiment - the South Essex. At its head is Col. Sir Henry Simmerson, accompanied by Simmerson's nephew Lt. Gibbons, Lt. Berry, Maj. Lennox (a veteran of the Indian Campaign), Capt. Leroy (a loyalist American) and Countess Josefina who is under the 'protection' of Lt. Gibbons. The South Essex is a battalion run by incompetents and filled with soldiers that have never been in battle. Wellesley is unimpressed by Simmerson and his regiment, but, as Simmerson is a political animal, he arranges a 'small victory' for him - blowing the bridge at Valdelacasa. Wellesley orders Sgt Richard Sharpe to see that the mission is a success in exchange for a promotion to captain. Simmerson is infuriated to learn that Sharpe is not a gentleman and was raised from the ranks by Wellesley. In revenge, he orders Sharpe to train his men to fire three rounds a minute by nightfall, or they will be flogged as punishment for failure. Sharpe and Harper succeed infuriating Simmerson even more. The following day, Simmerson orders Capt. Lennox to lead the South Essex across the bridge in an attempt to chase away a small French patrol. But the French cavalry appears as the new soldiers cross the bridge. They panic and are cut to pieces by the cavalry. Sharpe and the Chosen Men run to help the stricken unit. In his panic, Simmerson orders the bridge to be blown, leaving Sharpe and his men stranded. The French make off with the Colours, watched by Sharpe and the dying Lennox. Wellesley breaks up what is left of the South Essex and gives command of the Light Company to the newly promoted Captain Sharpe. Simmerson is outraged and threatens to use his influence in London to have Sharpe stripped of his rank. The only thing Sharpe can do to retain his rank is perform an act of outstanding valour. Sharpe vows to save the honour of the regiment by capturing a French Imperial standard: an eagle.

Portugal 1813 French, Portuguese and British deserters have banded together and taken over the village of Adrados. They are led by 'Marshal Pot au Feu' and Sharpe's old enemy, Obadiah Hakeswill, and they have two English women as hostages. Sarah Dubreton, wife of a French officer and Lady Isabella Farthingdale, the Portuguese wife of Sir Augustus Farthingdale. In Wellington's camp, Sharpe is putting Lt. Gilliland and his rocketeers through their paces. Sir Augustus Farthingdale arrives with the ransom for his wife but is appalled at the idea of Sharpe, raised from the ranks, taking it. Teresa escorts Sharpe and Harper part of the way to Adrados. When they get to the village, they spot two Frenchmen and assume they are deserters. They soon realise it is Sarah Dubreton's husband and his sergeant on the same rescue mission. The four men finally get to see the hostages, but Hakeswill has increased the ransom, giving Sharpe five days to come up with the extra money or the women will be raped. Dubreton tells Sharpe that Maj. Ducos, Napoleons spy master, has forbidden any extra payment. Sharpe decides to mount a rescue. Hakeswill escapes to wreak his revenge on Teresa. He is captured by Dubreton and handed over to the British to face justice. Nairn receives information that the French intend to invade Portugal from Adrados and decides to thwart the plan. Sharpe is promoted to Major and given command of the 60th Rifles in order to secure the safety of the women and prevent the French from taking the town.

Franco-Spanish Border, 1813 A carriage travelling through the countryside is ambushed by the French. Only a young nun escapes with her life, struck dumb with shock. Later, the same French company is attacked by the British. The French colonel shoots his captain and disguises himself in the captain's coat, claiming he is Capt. Dumas. Sharpe is suspicious, the man claims to trade in horses, but carries the best sword ever made - a Kliegenthal. He is also carrying papers covered in figures, which he says are bills, but could just as easily be codes. Col. Berkeley of the South Essex arrives and accepts Dumas' parole through an interpreter, Capt. Lord Jack Spears. The young nun gives herself up to Sharpe's protection. Unable to speak, she is given to Ramona to care for and given the name 'Lass'. Sharpe is told that a French colonel, Leroux, had been sent to capture a British agent, known only as El Mirador, whose identity is unknown. Sharpe is convinced that the captured captain is Col. Leroux, but he remains on parole instead of under guard. Sharpe is also convinced that the scraps of paper are a code and that the key lies somewhere in Voltaire's Candide, a copy of which was found when Dumas was captured. At Villafranca, Sharpe is re-united with his old adversary Sir Henry Simmerson. When Simmerson states the nearby French fort is no threat, a cannon is fired and Dumas escapes, proving he is Leroux after all. In the town, Sharpe meets Father Curtis who runs the hospital. When the fort is stormed, Sharpe is terribly wounded, Lass and Ramona refuse to give up and nurse him towards recovery. Meanwhile, Harris works hard in the library cracking the Voltaire code and Harper forges a new sword for Sharpe. If Sharpe recovers, there will be a spy to be found and a French agent to dispatch.

Winter 1813 A pro-Bourbon Noble, the Compte de Maquerre is in Wellington's camp, arguing that Bordeaux is ripe for rebellion, but Maj. Gen. Ross is dubious. He suggests using the Compte's castle, 60 miles behind enemy lines, as a base. Maquerre is reluctant, saying his mother and sister had turned it over to Napoleon, so it must be captured. Col. Horace Bampfylde is to lead the attack, with Sharpe in support. There is sickness in the camp and Maj. Gen. Ross and Sharpe's new wife, Jane, succumb to it. The only cure is quinine which is in short supply. When they reach the castle, Col. Bampylde wants the glory, he sends Sharpe, Capt. Frederickson and the Rifles scouting, so he can take the castle alone. He fails in his mission, but gains heavy casualties. Sharpe sees what is happening from afar. He infiltrates the camp and forces the French to surrender. Bampfylde returns to the castle and sends Sharpe and his men away. Maquerre returns with the mayor. They tell Bampfylde that the region has changed sides, Gen. Calvet is on his way and Sharpe is dead. Bampfylde is persuaded that he has accomplished his mission and returns to tell Wellington. Sharpe and his men ambush a French convoy and capture a small supply of quinine. He also finds out that the region is far from ready to rise against Napoleon, and concludes that Maquerre is a double agent. When he returns to the castle, he finds it deserted except for the wounded, along with Maquerre's sister and sick mother. Gen. Calvet is heading towards the castle, and Sharpe and his men are desperately short of ammunition.

Toulouse - April 1814 In the French camp, Ducos watches as Napoleon's fortune is loaded on a cart. If Toulouse falls, the treasure will be removed before the British, or the Bourbons, can steal it. Sharpe writes a note giving Jane power of attorney over his money. She makes him promise this will be his last battle and that he will then return to England with her. On the battlefield, Calvet realises he is losing, as the British gain ground, and Ducos is ordered away with Napoleon's treasure. In the British camp, the officers celebrate their success with a dinner at which one of them, Col. Wigram, insults Sharpe. A duel is arranged with Capt. Frederickson acting as Sharpe's second. Ducos tests the loyalty of the men escorting the treasure by asking if they would consider stealing it. One officer, Maillot, declines and Ducos orders him back to his home in Normandy. In the British camp, Jane's friend, Molly Spindacre, tells Jane that Sharpe has challenged her 'protector', Col. Wigram, to a duel and broken his word to Jane. After finding out that Jane has power over Sharpe's money, she persuades Jane to return to punish Sharpe. Once there, they obtain all the money and start spending it. When it is discovered that Napoleon's treasure has been stolen, the French suspect Sharpe and he is arrested in his quarters. During his court martial, it is requested that Maillot give evidence. Ducos finds this out and has to prevent Maillot from accusing him, so he arranges his murder and has Sharpe set up. Then he sets sail to safety in Naples. In London, Jane is informed of Sharpe's arrest by Lord John Rossendale. She faints into his arms, and he falls for her 'charms'. Sharpe escapes from custody and makes for Normandy to find Maillot. Before he can reach Normandy, Maillot is killed and Sharpe is the suspect, getting shot by Maillot's sister, Lucille. When Frederickson, who accompanied Sharpe, explains what has happened, Lucille helps to nurse Sharpe back to health. In London, Jane has fallen for Rossendale and they are lovers. Harper sees them together and returns to France. Frederickson tries to track down Ducos and discovers Gen. Calvet on the same mission. They believe their man has gone to Naples, and once they have collected Sharpe and Harper, they agree to join forces to recover the treasure.

France 1813 Col. Cresson and Gen. Calvet plan to capture Wellington's intelligence chief, Maj. Gen. Ross. Gypsies are camping with the British, their women are causing a stir among the soldiers and Sharpe has settled into married life. Jane, however, is bored and looking to the future. She wonders how Sharpe will take to the social life back in England. Col. Brand also arrives in the camp, he operates behind enemy lines and plans to destroy Calvet's powder supply. Sharpe is to act as his back up. They also need the services of explosives expert, Maj. Septimus Pyecroft. A war correspondant and poet, called Shelligton, has also arrived and becomes enamoured with Jane. When Ross and Sharpe meet Pyecroft, he has a gypsy girl with him who was the only survivor from an attack on her family. In the camp, she recognises her family's horses among those belonging to Maj. Brand's men. Another gypsy girl, sets herself at Harris, but when he goes to her tent in the evening, he discovers her and her family dead. When he reports the murder, he finds himself chief suspect and is confined to camp. Sharpe asks him to watch over Jane while he is away. Shellington accompanies Sharpe, but tires of war and is escorted back to camp. The murderers are uncovered and rounded up, and Sharpe also discovers there is a French spy in the camp.