In 1857, freshly-arrived Sandhurst-trained Captain Alan King, survives an attack on his escort to his North-West Frontier Province garrison near the Khyber Pass because of Ahmed, a native Afridi deserter from the Muslim fanatic rebel Karram Khan's forces.

As soon as his fellow officers learn that his mother was a native Muslim (which got his parents disowned even by their own families), he encounters prejudiced discrimination, including Lieutenant Geoffrey Heath moving out of their quarters.

Brigadier General J. R. Maitland, whose policy is full equality among whites, learns that King was raised with Karram Khan, and charges him with training and commanding a native unit, the Khyber Rifles.

King volunteers to engage Karram Khan, the only man who can bring the normally divided local tribes together in revolt, pretending to have deserted.

They were going to make it with Richard Greene or Victor McLaglen,[5] but plans were pushed back because of the start of World War II.