In the Qin Dynasty, time traveller Hong Siu-lung (Louis Koo) has lived in seclusion with his family for twenty years, yet every step he takes remains under the watchful eye of his former disciple, now the Qin Emperor (Raymond Lam).
On the brink of ultimate power after conquering the six warring states, the emperor is suddenly ambushed by a mysterious team wielding advanced weapons that clearly originate from Hong’s time. Drawn together by fate once more, Hong and the Qin Emperor are forced to confront the long-buried conflict between them, as the future now depends on how they settle their past.