Based on one particular storyline from The Water Margin, Three Sinners weaves an intriguing story of romance, treachery, and death, all within the context of the traditional Huangmei Opera. Yan Jun casts his real-life wife, the elegant Li Li Hua, star of such Shaw Brothers films as The Goddess of Mercy and Vermillion Door, as one of the title characters, a woman who finds herself in the middle of a stormy love triangle involving her controlling husband (director Yan Jun serving double duty in a starring role) and a passionate lover (Chen Yan Yan).

Ling Bo is Lin, a young man engaged to the daughter of a rich man, who now despises Lin because of his family's declining status. Lin visits his beloved fiancee before he heads towards the imperial city to participate in the civil service examination, only to find her maid lying dead in blood. Lin is then accused of murder. How can Judge Bao prove his innocence?