A group of evil bandits are terrorizing the land from their invincible mountain castle. The high commanding official decides to put a stop to this and commands one of his officers to gather a group of Kung Fu masters to put an end to the terror. But everything is not that simple and straight-forward, as we quite soon learn when the plot thickens.
Direction
Cheng Kang's claustrophobic castle corridors amp the tension.
Acting
Ku Feng's weaselly Water Rat steals every scene he's in.

Director
Cheng Kang
Trivia, insights & behind the scenes
Cheng Kang directed this during Shaw Brothers' golden age of wuxia, when they were pumping out 50+ films a year.
The 'invincible castle' premise became a Shaw Brothers template—see also The 14 Amazons and The Water Margin.