During the days of the British Raj on the North-West frontier, a British army regiment is ambushed by Indian rebels from the mountains above. The British are anxious about the use of machine guns in the attack, and a message is immediately deployed to the Governor of the North-West province of Garrison City. The Governor orders a message to be sent to Captain Carruthers, working undercover in the Doro Pass. Disguised as a beggar, Carruthers receives the message which requests his return to Peshawar.
Upon returning, he is asked to report to the Governor and also learns that the Governor is throwing a farewell party that evening for his niece, Miss Margery Brock. Carruthers discusses with the Governor his ideas on establishing a British presence in Tokot, capital of one of the frontier states, and suggests offering a treaty of protection to the Khan, who wishes to ensure the succession of his son, Prince Azim, to the throne. Meanwhile, in the barracks, a group of British band members are discussing the upcoming party that evening, at which one of them, Bill Holder, will be playing.
At the party, Carruthers joins Margery and Lieutenant Escott. She asks Carruthers about his time hunting (a cover for the time he has spent undercover) and the couple move outside, where the conversation grows more intimate. He proposes marriage and she accepts. The Governor offers his congratulations and informs Carruthers that he will soon have to go to Tokot to instigate his plans.
Several weeks later, as the British near the palace, they hear the banging of the Sacred Drum of Tokot which is sounded to welcome them. Almost immediately afterwards, they are shot at from the hills until Prince Azim arrives and swiftly deals with the perpetrators, ordering their execution. But Carruthers is suspicious of such swift punishment and challenges him. The Prince confesses that he ordered the shooting to test whether the British were "easily frightened" and promises to try to tell the truth in the future.
At the Palace, Carruthers and the Khan agree the treaty on behalf of their people, which benefits the British by ensuring the suppression of arms trafficking across the state while providing the people of Tokot with British protection from neighbouring tribes. Meanwhile, the Khan's brother, Prince Ghul talks to his supporters about his plans for victory in the upcoming war. He mocks more traditional methods of battle by declaiming the preaching of the old Mullah, and talks of the importance of planning and weapons. Prince Azim also meets Holder at the palace and, after a misunderstanding, they become friends. Holder invents a special signal on the drums for the Prince, which Azim says he will use whenever he is in danger.
The British leave Tokot and Prince Ghul murders his brother. Plans are less successful for the murder of Prince Azim, who escapes to the neighbouring city of Peshawar. The British are informed of the murder of the Khan but are unaware of his brother's involvement. Prince Ghul assures the British that he will respect the treaty, and the Governor decides to send Carruthers to Tokot as Resident. Meanwhile, an assassin has followed Azim and attempts to stab him, but he runs to the nearby house, which belongs to Carruthers. The Captain is not home but Margery Carruthers sees the boy is hurt and protects him from the assassin by drawing her gun and calling the guards. The assassin is killed and Carruthers arrives home but realises that the Prince is not safe with them and they part.
In Tokot, Carruthers and Prince Ghul meet formally but Carruthers is aware he must be cautious. Mohammed Khan, who has earlier shown allegiance to the old Khan, hears of a plan to kill the British at a banquet held by Prince Ghul at the palace. He attempts to warn Carruthers but disappears before the meeting can take place. Prince Ghul goes in his place and invites Carruthers to the final celebrations of the Great Feast. Preparations are made at the palace as machine guns are positioned facing the British seating.
Back in Peshawar, Prince Azim receives news that tribesmen are gathering for war and that his uncle will be slain after he has helped to overpower the British. Azim is alarmed because his friends, the Carruthers, will be involved. The Prince attempts to speak with the Governor but refuses to believe Azim without confirmation. Prince Azim rides alone to Tokot to warn Carruthers.
Meanwhile, Carruthers and Escott arm themselves while preparing for the banquet. At the feast, Carruthers and Prince Ghul discuss differences between their cultures and watch the entertainment. The Prince awaits the third drum as a signal for the shooting to begin. Azim arrives and struggles to the drum which he begins to beat in the rhythm Holder had shown him earlier. Carruthers knows immediately that this signals danger and raises the alarm but the guns start firing. Escott is shot and dragged to safety but Carruthers is shot and captured by Ghul, and is taken to the tower, where Mohammed Khan has been tortured and kept hostage.
British troops arrive, on order from the Governor who has received confirmation of Azim's story. Ghul learns that the army has crossed the border and orders the executions of the two prisoners. A battle ensues at the Palace but Carruthers, who has been released, corners Prince Ghul and kills him. Peace is restored in the state of Tokot and the British bid their farewell.
