The film is adapted from a novel by Rosemary Suttcliffe. A young Roman soldier came to Britain in 135 AD to investigate the mysterious disappearance of the 9th Army of Rome in Scotland 20 years ago. It tells that in 140 AD, the Roman Empire expanded its territory to Britain, but it failed to completely occupy Britain. The rebel tribes of (Scotland) still occupy the far north. Marcus Aquila ( Channing Tatum ) came to Britain, determined to restore his father Flavius's ruined reputation. Twenty years ago, 5,000 brave soldiers of the Ninth Eagle Regiment of Rome, under the leadership of Flavius, carried the golden eagle and marched north to Caledonia. They never returned. The legion and the eagle all disappeared into the mist. The furious Roman emperor thus ordered a wall to be built to separate the territory from the north. Hadrian’s Wall thus became the northernmost border of the Roman Empire—the edge of the civilized world.
Marcus, who was determined to be an excellent fighter, was assigned to garrison a small fortress in the southwest, in charge of a corps. He bravely led the soldiers to battle with the enemy, was seriously wounded, received the honor of the empire, but lost the title of warrior. The depressed Marcus stays in his uncle ( Donald Sutherland )'s residence to recover from his injuries. In a Gladiator game, Marcus saved the life of a young Briton on an impulse. Then his uncle bought the Briton-Esca ( Jamie Bell ) and made him a servant of Marcus. Marcus despised Esca, and Esca hated everything in Rome. Nevertheless, Esca swore allegiance to the Roman who saved his life.
After hearing the rumor that the eagle appeared in a tribal temple in the north, Marcus decided to recapture the eagle and embarked on the journey with Esca. They crossed Hadrian's Wall to the vast and treacherous wilderness of the Caledonian Highlands. Marcus must rely on the help of his servants to find his goals. On the way, they met the former Roman soldier Gaeln (Mark Strong), and Marcus realized that his father's disappearance was probably related to the loyalty of his servant and the secret of his life experience. When the master and servant collided with the ferocious Prince Sil (played by Taha Rahim), the secret became even more confusing.
