Snake Agent (Electronic book text)

When a soul goes missing, an occult detective ventures into Hell to retrieve it
When the fourteen-year-old daughter of Singapore Three's most prominent industrialist dies of anorexia, her parents assume that Pearl's suffering has come to an end. But somewhere along the way to the Celestial Shores, Pearl's soul is waylaid, lured by an unknown force to the gates of Hell. To save their daughter from eternal banishment, they come to Detective Inspector Wei Chen, whose jurisdiction lies between this world and the next.
A round-faced cop who is as serious as his beat is strange, Chen has a demon for a wife and a comfort with the supernatural that most mortals cannot match. But finding Pearl Tang will take him further into the abyss than ever before--to a mystifying place where he will have to cooperate with a demonic detective if he wants to survive. It's easy, Chen will find, to get into Hell. The hard part is getting out."
Snake Agent "is the first of the five Detective Inspector Chen Novels, which continue with "The Demon and the City "and "Precious Dragon."