In 1918, retired General Brunswick tells officers in a London men's club the true story of how he got his promotion years before: In Mirzabad, India, a source of irritation to infantry colonel Brunswick and his devoted aide, Captain Pindenny, are three privates, Archibald Ackroyd, Dennis Malloy and Jock Sykes, who, though excellent combat soldiers, spend their free time drinking and brawling. One afternoon, Brunswick receives word that he must march his battalion to rendezvous with cavalry troops led by Colonel Groat. The privates are interrupted in some drunken revelries and compelled to join the rest of the soldiers in the march. At an encampment near the town of Chotapur, Ackroyd masterminds a plan to enable him, Malloy and Sykes to go into town, where they spend the night drinking and gambling. They return to camp the next day, still drunk, and carried on an elaborate litter. Their arrival causes embarrassment for Brunswick, who has just been met by Groat and learned that his rival will be taking over the command. Brunswick and Pindenny pretend that the men have been on a secret mission, but later, after the privates get into a fistfight with some of Groat's men, a frustrated Brunswick tells Ackroyd, Sykes and Molloy that they must be separated. To accomplish this, Brunswick says that one of them, and he does not care who, will be made a sergeant. Although none want the dubious honor, Ackroyd is selected after Sykes bribes Molloy to vote with him. At first the three friends are merely sad, but soon start to argue over Ackroyd's new status as a sergeant. As the battalion begins its march back to Mirzabad, Ackroyd is openly hostile to his former friends, just as they are to him. One night, a group of herders move their cattle through the encampment, causing considerable disruption. After they leave, Pindenny sends Ackroyd to assess the situation and learns that the rifle tent was pilfered. Off the record, Pindenny asks Ackroyd to select some men to recover the weapons, and Ackroyd agrees on condition that Pindenny take his sergeant's stripes away. With Pindenny leading Ackroyd, Molloy, Sykes and the others, the herders are located across a nearby river. Because he cannot swim, Sykes holds onto a raft containing the men's clothes. When he loses hold of the raft and goes under, Ackroyd saves his life, thus reuniting the three old friends. Once on shore, Ackroyd, who is the only one who kept on trousers, is sent to find more clothes. One of his female friends, Crenshaw, who lives nearby, gives Ackroyd clothing, but they are all articles of women's lingerie. The men are able to overcome the herders and retake the guns, but must return to camp in the lingerie. Pindenny, who has appropriated Ackroyd's army trousers, leads the band back to the encampment riding one of the bulls. Although the mission was successful, Groat is disgusted by Brunswick's unorthodox command, and the frustrated Brunswick implores the men not to try to help him any more. The next day, Groat tells Brunswick that he must assign fifty men, twenty-five of the best from each of their commands, to advance with ammunition to the deserted Fort Imara. Brunswick soon deduces that the men are being sent into rebel territory as a sacrifice to save the rest of the regiment, and detests Groat for the order. The men leave, including Pindenny, Molloy and Sykes, but not Ackroyd because Pindenny had been unable to demote him back to private, and another sergeant is assigned. After they leave, Brunswick is ordered to march to another barracks and wait, but when he hears that Ackroyd has deserted, Brunswick sees his chance and takes his men to Imara, purportedly in pursuit of a deserter. Meanwhile, at Imara, the English soldiers are overrun by rebels led by Manik-Rao. The survivors take refuge in the ammunition room, which Manik-Rao bolts shut. This is observed on a hilltop by Ackroyd, who then sneaks into camp, overpowers a rebel guard and changes clothes with him. Moments after Manik-Rao offers the English one last chance to surrender before the ammunition room is dynamited, Ackroyd sneaks up to a side window to talk with the men. Just then, they hear the bugles of Brunswick's battalion in the background. Ackroyd is subsequently sent back and forth to report on what is happening. Brunswick is met by rebel leader Govind-Lal, Manik-Rao's estranged father, who offers to surrender to prevent a bloodbath. Manik-Rao refuses to follow his father's wishes and says that the English will die first, then sets the fuse on the dynamite. The English then start shooting at the rebels and in the melee, Ackroyd kills Manik-Rao and snuffs out the dynamite fuse in time to save his comrades. After Brunswick's troops crash through the fort's gates, they are finally victorious. Later, when Brunswick meets with Groat, expecting to be court-martialed, he learns that Groat had planned for events to unfold as they had, knowing that Brunswick would not allow his men to die. Groat also informs him that the ammunition was actually blanks. Brunswick is then promoted to general and Ackroyd's punishment for desertion is removal of his stripes. At the end of his story, Brunswick offers a toast to Ackroyd, Sykes and Molloy, "The Queen's hard bargain."