Set in 1857 along the North-West Frontier near the Khyber Pass, Captain Alan King, [Tyrone Power], freshly arrived from Sandhurst, finds himself at a frontier garrison where survival hinges on more than luck. He endures an early ambush that is thwarted thanks to Ahmed, a native Afridi deserter from the rebel forces led by Karram Khan. King, born locally and fluent in Pashto, moves through a web of prejudice tied to his mixed heritage. The tension sharpens when Lt. Geoffrey Heath, [John Justin], openly distances himself from King’s quarters, a stark reminder of the social fault lines that ripple through the troops.
Brigadier General J. R. Maitland, [Michael Rennie], champions a bold policy of equality among whites and sees in King a rare bridge to a native force. He assigns King to train and command a native unit, the Khyber Rifles, hoping to unify disciplined British leadership with fiercely loyal local fighters. This decision stirs both hope and skepticism among the ranks, setting the stage for a fragile alliance that could alter the balance of power in the region.
The general’s daughter, Susan Maitland, [Terry Moore], is drawn to King’s courage and complexity. A kidnapping attempt—foiled by King—threatens to derail any budding romance, prompting Maitland to decide that Susan should be sent back to England to keep her safe. Yet the pull between duty and desire remains, complicating the political and personal calculations for everyone involved.
To counteract the rift and to strike at a man who could rally divided tribes, King volunteers for a dangerous ruse: he will pretend to desert and lure Karram Khan into a trap. He travels to the Khyber Pass and presents himself as a defector, hoping to gain entry into the rebel leader’s confidence. The plan hinges on trust and a shared history, for Alan and Karram Khan once knew each other and speak of a past that blurs the lines between ally and foe.
The reunion is loaded with tension. Alan admits that he sees Susan as more than simply the woman he loves, and Karram probes the truth of his feelings. In a moment of precarious honesty, Alan reveals the depth of his love for Susan, even as the loyalty he owes to England complicates his loyalties to those he’s come to respect among Karram Khan’s circle.
As loyalties shift, Alan is captured and bound alongside other British officers. Karram’s men kill several of his comrades, but Alan’s life is spared when he chooses to spare Karram’s life in a moment of unexpected mercy. He returns to Maitland with a report of what transpired, and Lt. Heath confirms that Susan has left with the other women, though she shares the same feelings for Alan as before.
When an uprising looms, the conflict over technology and tradition resurfaces in a practical dilemma: the Khyber Rifles refuse to use the new Enfield rifles because the cartridges require grease, and consuming pig grease violates their religious prohibitions. Alan, who is half-Muslim, demonstrates that using the rifle is not inherently against their beliefs, helping to bridge a crucial gap. This nuanced moment allows the rebels to reconsider their stance and proceed with a combined force.
Despite the hesitation, the Khyber Rifles decide to fight with knives, relying on their skill and courage rather than firearms. In a bold assault, Alan leaps onto the enemy’s camp and faces Karram Khan in close quarters. As the struggle intensifies, one of the Khyber Rifles drives a knife into Karram Khan’s back, turning the tide of the battle. Victorious, the Khyber Rifles return to the fort, and General Maitland welcomes Alan back, recognizing a future that includes Susan for him.
