Under the guidance of ruthless warrior King Andragoras III, the kingdom of Pars prospers, while the naive and gentle prince Arslan trains to continue his father's legacy. Arslan believes Pars to be a joyous and righteous land, until a captured slave his age from the hostile nation Lusitania escapes and takes him hostage, revealing to Arslan the horrors and cruelty slaves are subject to. Arslan is rescued, but the encounter leaves an impression on him.

Three years pass, and Arslan's first battle against the Lusitanian army has come. Through the Lusitanian use of spies and traps, the battle ends in disaster, and the majority of Parsian troops are slain. With the aid of his loyal friend and bodyguard Daryun, the stricken prince barely manages to escape with his life. With his father nowhere to be found and his homeland now occupied by the enemy, Arslan loses everything in one fell swoop.

Seeking shelter, Daryun takes the prince to his friend Narsus, an eccentric but brilliant strategist. With the help of Narsus and various other people he meets along the way, Arslan begins his campaign to reclaim his kingdom. The path is riddled with many challenges, from the greedy nobility to the mysterious warrior known as Silver Mask. Nonetheless, Arslan refuses to falter in his mission to save Pars from both its enemies and its own corruption.