In 1850, a British garrison defends Fort Kandahar on the North West Frontier of British India. Lieutenant Case is a mixed race British officer under the command of Colonel Drewe. Case is despised by his colonel and a few jealous fellow officers for being part-native. However, due to his background, Case is useful to the British who use him to infiltrate the local tribes. The tribes, united under a war chieftain named Ali Khan, have been fomenting revolt against the British colonial forces. Disguised as a native, Lieutenant Case collects valuable intelligence for his regiment. Unfortunately, during a spying mission, Case and a fellow officer, Captain Connelly are discovered. Case escapes under the cover of darkness but Connelly is captured. On his return to Fort Kandahar, Case is accused of deliberately abandoning Connelly to the enemy and of cowardice as he made no attempt to rescue Connelly. The love affair between Connelly's wife and Case is well-known at the fort and many officers suspect that Case abandoned Connelly to his fate in order to have Connelly's wife. When Case is court-martialed, he defends himself against these accusations but the court mercilessly discharges him from the army and sentences him to 10 years in the brig. Case's native man-servant comes to visit Case in the fort's prison and eliminates the guards, freeing Case. The two run away in the desert where the servant reveals to Case that he is in fact a spy of Ali Khan. He takes Case to the rebel chieftain who offers to hire Case to work for his rebellious tribes. Emboldened by revenge against his former commander, Case accepts to work for Ali Khan and train his troops, provided they don't attack or harm civilians or captured prisoners. Case and Khan's sister Ratina become good friends. Case and Khan gradually learn to trust one-another. But for the British, Case is an escaped prisoner and a traitor. The British place a bounty on Case's head. Unfazed by this, Case continues to train Khan's men, fight numerous skirmishes against small British patrols and prepare for the upcoming assault against Fort Kandahar. The fort's commandant requests and awaits reinforcements from other nearby forts. However, Case has conflicting feelings. On one side he hates his former commander and wishes to kill him and on the other side he still thinks of himself as being British.