The story begins with the country experiencing a significant increase in circulation of counterfeit coin currency, leading to growing unrest and instability.

Once inside, Cold Blood is surprised to observe that the Divine Constabulary staff live and work together more like a family than a highly formalised professional security force.

Cold Blood finds his loyalties divided, and things are made harder as he becomes tangled in a love triangle with two girls, one from each agency.

The Four features characters from a continuing series of wuxia novels by Malaysian Chinese writer Woon Swee Oan.

The novels have been adapted for some television series in Hong Kong, Taiwan and China, including ATV's The Undercover Agents[2] and TVB's The Four.