20 years ago, the powerful Roman Empire sent out the Ninth Roman Legion, composed of 5,000 elite soldiers, but mysteriously disappeared in the Scottish Highlands. Marcus (Channing Tatum), the son of the leader of the Ninth Legion, was brave and good at fighting, leading his troops to fight on the front line. Because he was seriously injured in a war, he had to recuperate at his uncle's house. During his recovery, Marcus rescued a slave, Esko (Jamie Bell), in the arena and took him in as a servant. Not long after, Marcus heard that someone in a northern tribe had found the eagle stick that his father had lost. Determined to win back the honor for his father, he decided to go to the north to get the eagle stick back. Marcus set off with Esko, who was more familiar with the northern environment. The relationship between the master and servant experienced various ups and downs and mutual tests on the way. Especially when they met the fierce Prince Seale (Tahar Rahim), Marcus discovered that Esko's identity was far more than just an ordinary slave. Who controls the Eagle Staff? How did the Ninth Legion fall? The truth is becoming more and more confusing...