During the brutal Warring States period in ancient China, two war orphan slaves named Xin and Piao share a single, powerful dream: to rise above their lowly status and become the greatest generals the world has ever seen. They train together every day, honing their skills with wooden swords and vowing to one day achieve glory on the battlefield. Their bond is shattered when a retainer of the Qin royal court arrives and selects Piao to serve within the palace, leaving Xin behind.

Soon after, a mortally wounded Piao stumbles back to their village. With his last breath, he reveals he was used as a body double for Qin's young king, Ying Zheng, and was caught in a violent coup d'état. Before dying, Piao urges Xin to travel to a specific location to carry on his will. Following this request, Xin meets Ying Zheng, a mysterious and determined young man who bears an uncanny resemblance to his late friend. The current king is locked in a power struggle with his ambitious younger half-brother, who has seized the throne.

Initially driven by rage over Piao's death, Xin decides to join forces with Zheng. He pledges his sword to help the deposed king reclaim his rightful place as the ruler of Qin. This marks the beginning of Xin's journey from a simple servant to a respected warrior. Together, they survive a series of intense political and military confrontations, successfully restoring Zheng to power and setting their shared ambition in motion: the unification of all of China's seven warring states under the banner of Qin.

As the series progresses, the scope expands dramatically from this initial palace intrigue. Xin joins the Qin military as a unit commander, leading his own small band of soldiers into large-scale, historically inspired conflicts. He meets key allies, including the strategic prodigy Diao, who becomes one of his closest advisors. The story follows Xin as he fights under legendary generals, participates in massive campaigns against rival states like Zhao and Wei, and slowly climbs the ranks of the military. Throughout it all, he must rely on his immense strength, unyielding spirit, and cunning strategies to survive on battlefields where tens of thousands of men clash for supremacy, all while staying true to his vow to become a Great General of the Heavens.