Set around 2050, the story begins when Wee Ming, daughter of a powerful Hong Kong Triad boss, goes missing and a trio of mercenaries goes looking for her. They aren't out to rescue her but to snatch her before her father's men do and ransom her back. Wee Ming has slipped into the fictional Shan Xi protectorate, a region where the group's femme fatale leader, Hana Tsu-Vachel, once worked in a brothel. Arriving in Hong Kong with her partners Royce Glas and Jacob "Deke" DeCourt, what should be a simple grab spirals into disaster: Wee Ming's father, Mr. Lam, owes his fortune to a pact made long ago with demons, and his daughter — a paper doll given life — is destined to be sacrificed to Yim Lau Wong, the mythical King of Hell.
After Hana's inside contact Jin is tortured and killed and Glas is driven into Lam's building by a VTOL jet, the mercenaries are forced off a bridge and regroup downriver, where they spot Wee Ming amid a burning village before being scattered by undead villagers. Pursuing her through a hostile military train and into Madam Chen's restaurant-brothel, the group is picked apart: Glas loses an arm to Mr. Lam, Deke is murdered, and Wee Ming's powers erupt after she is splashed with Deke's blood, turning Chen and her thugs into demons. Hana kills the demon-disguised Chen, but Mr. Lam escapes into a portal to Hell with his daughter, and Hana follows, with a revived Glas giving chase.
In Hell, Hana meets the Guards of Impermanence, Glas battles the demonic, tortured corpse of Deke, and Yim Lau Wong reveals that with Wee Ming returned to the netherworld he can expand Hell to swallow the Earth — explaining that Hana was chosen as guardian for her ruthlessness. When Glas tries to kill Wee Ming, the player chooses who dies, determining the final boss and the ending. On Hard, a third option spares them both: Hana and Glas emerge from the ruins to find Deke alive on a toilet with no memory of his death, while Glas discovers his severed arm fully restored, and the three walk off into the sunrise to continue their exploits.