In the Ming dynasty of China, Shen Lian (starring Chang Chen), a secret police of corrupt government, is trapped by the conspiracy on a mission. To prove the innocence, he seeks the truth with a girl called Bei Zhai (starring Yang Mi).

An imperial guard searches for the truth behind a conspiracy that framed him and his partners. The proof of his innocence lies with a wanted woman named Bei Zhai, but will she reveal what she knows? In this intense prequel to Brotherhood of Blades, the only thing he can truly trust is his sword.