A rather loose adaptation of the novel that follows the original story's plot rather faithfully, Shaw newcomer Ng Yuen-Jin (who seemingly never achieved the same level of popularity of his co-stars) plays the lead role as Di Yuan, a martial arts trainee framed for a crime over a conspiracy involving a hoard of hidden treasure. Imprisoned with a fellow convict, Ding Dian (Jason Pai), who is serving life sentence due to similar circumstances, as a twist of fate turns out, Ding Dian is actually an expert martial artist who decides to pass his skills to Di Yuan and help him in his quest for revenge.
Yueh Hua and Rachel Shih Szu, who previously co-starred in numerous Shaw productions, notably in The Young Avenger and Trilogy of Swordsmanship, collaborates again, ironically this time as the main villain and the villain's daughter. This is also Shih Szu's last work with Shaw Brothers, having been part of the studio's mainstay ever since The Lady Hermit nine years ago, where she eventually left and returned to her native Taiwan to star in films from her home country.
The director, TF-Mou, is better known for his later film, the CAT-III classic Men Behind the Sun.
A Deadly Secret contains examples of:
- All Monks Know Kung-Fu: Played straight with the villainous monks of the Blood Saber Sect.
- And I Must Scream: The fate of Lady Ling huang-hua, after she gets Buried Alive by her father, Magistrate Ling when she tried to expose his conspiracy. The truth behind her demise is exposed when Di Yun digs out her coffin... and realize her arms are propped upright against the lid.
- Big Bad: Magistrate Ling, played by Yueh Hua during the period of his career where he started taking villainous roles.
- Compressed Adaptation: Due to adapting the source material, a 400-page novel, into an 80-minute film. For instance, the film literally starts with the protagonist being thrown into prison, with the Frame-Up in the novel being left out and later shown in brief flashbacks.
- Corrupt Politician: Magistrate Ling is secretly working with a legion of bandits to uncover a hidden cache of valuable pearls, and have no qualms killing everyone who gets in his way to obtain the treasure - including his own daughter. He's also behind the conspiracy that results in loads and loads of deaths throughout the film, using his power to instigate all the killings to cover his back.
- Dead Man Writing: The location of the hoard of pearls is carved in the interior of a coffin board... by the fingernails of Lady Ling, having been Buried Alive, before she succumbs.
- Death by Materialism: The fates of Magistrate Ling and all his mooks. The pearl horde they're after? It's poisoned pearls. They all end up dead in minutes after grabbing the pearls.
- Driven to Suicide: After Di Yun's first night in prison, his cellmate, Ding Dian wakes up to see him having hung himself by the neck. Ding Dian however got him down and revives him.
- Laser-Guided Karma: Magistrate Ling, who orchestrated a massive conspiracy that leads to numerous deaths and suffering to covet a hoard of valuable pearls for himself, even having his own daughter killed to Leave No Witnesses, ends up getting fatally poisoned by the toxic coated on the pearls.
- Mentor Occupational Hazard: Di Yun's mentor, Ding Dian, ends up being poisoned and killed near the end of the film. It's a wuxia, you can predict this outcome from a mile away.
- Obfuscating Stupidity: The haggard-looking old prisoner that everyone treats as a fool, who becomes Di Yun's cellmate when Di ends up being thrown into prison? He's actually Ding Dian, a retired kung fu master and former assassin, who then passes his skills to Di Yun so that he may seek revenge against everyone responsible for his imprisonment.
- Offing the Offspring: Magistrate Ling buried his own daughter, Lady Ling, alive in a coffin when she tried to expose his conspiracy.
- Shovel Strike: A shovel-vs-sword fight happens late in the movie when Di Yuan, unarmed in the middle of a graveyard, uses a shovel as an impromptu weapon against the magistrate's mooks.
- Sinister Scythe: Scythes are the default weapon used by the corrupt monks of the Tibetan Blood Saber Sect.
- Worthless Yellow Rocks: Towards the end of the film, Magistrate Ling and his minions have finally found the giant Buddha statue filled with pearls, and immediately orders the statue to be smashed open, spilling pearls the size of tennis balls all over the interior of the cavern. Too bad the pearls' surfaces have been coated with a deadly poison, and Ling's minions, as well as Ling himself, having grabbed and shoved all the pearls into their robes, ends up dying horribly one after another.