Fok Tats scheme to raid a convoy of government reserve is intercepted by 'Ghost Knight'. Chau Ping, an accomplice of a corrupt official, declares wars on Fok whom he believes has ties with the mysterious raider. A meeting was convened by Ghost Knight to settle the dispute. Tat's son Sze-chuen learnt that his maid Ma Yuk-lan is the daughter of a general of the ousted Ming court who has donned the mask of a knight-errant to protect the son of the Ming minister Sze Ho-fat, Sze-chuen himself. Back in Deadly Valley, an impostor of Ghost Knight was caught. Slashing at the father, Sze-chuen is disheartened to learn that the faker, Ma's mother, has been transferred to the enemy camp in a feigned surrender orchestrated by Sze while an uprising is gathering momentum funded with money robbed from the corrupt official. Ma teams up with the father and son to storm the Chau Fortress and rescue Ma's mother. The couple champions the restoration of the old empire with Sze's seal.
Unfortunately the movie The Mysterious Heroine is not yet available on HBO Max.
| Directing | Lung To | Director |
| Writing | Lee Yuen-Man | Screenplay |
| Writing | Pong Chau-Wah | Screenplay |
| Production | Law Shun-wah | Executive Producer |
| Production | Wong To | Producer |
| Production | Lee Kit-Fong | Producer |
| Writing | Ma Wan | Original Story |
| Directing | Fung King | Assistant Director |
| Crew | Wong Kat-sing | Cinematography |
| Editing | Sung Ming | Editor |
| Art | Chiu Chuen | Art Direction |
| Crew | Leung Hoi-Shan | Sets & Props Artist |
| Sound | Mui Ching | Recording Supervision |
| Sound | Lee Yuen-Man | Musician |
| Sound | Pong Chau-Wah | Musician |
