Orphan and servant Piao is unexpectedly invited to work at the Royal Court; some months later, he returns to his village, mortally wounded; before he dies, he sends his friend Xin off to a dangerous village, where Xin has a shocking encounter.

Xin discovers Ying Zheng, the young King of Qin, who's fleeing his half-brother's uprising; when Piao's killer arrives to murder Ying Zheng, Xin, who's learned that Piao died serving as Zheng's stand-in, must decide which to help and which to kill.

Xin, Zheng, and the King entrust their escape to young Diao, who knows a secret way out of Heibei Village; Xin still blames Zheng for Piao's death, and even as this simmering conflict boils over, a new and deadly pursuer takes up the chase.

Fleeing pursuit, Zheng and Xin struggle with exhaustion and with each other; when they reach the appointed meeting site, there's no sign of Zheng's sole supporter, Lord Changwen, and the murderous tracker Mu Ta is hot on their trail.

Xin, who's vowed in the name of his ambitions to help the King, must single-handedly face the treacherous assassin Mu Ta; meanwhile, General Wang Yi brings a piece of tribute to the Court that seems to spell the end for all young King Zheng's hopes.

Xin hears a tale of Piao's heroism during Wang Yi's ambush, but he also learns that King Zheng has even fewer allies than he'd been told; with little time left to forestall a civil war, Zheng decides on a dangerous path to seek out unlikely allies.