Hardhearted and smart Mo Ching (Lam Raymond) became crippled when he was young.

The series is adapted from Woon Swee Oan's novel Si Da Ming Bu (The Four Great Constables). The novel tells the story of four young constables: Heartless, Iron Fist, Chaser, and Cold Blood, who work together to solve cases and attempt to bring down the corrupt Prime Minister of the Song Dynasty.