Taki is assigned to go after Daishu, a businessman who is suspected by the police to be selling the drug "happiness", a drug from the Rapter's world that causes people to "evaporate" if they stop taking it. Actually it is another group of Rapters that are selling the happiness. The second group attacks Daishu's group, and eventually Taki, Daishu, and Daishu's daughter join forces to fight the evil Rapters. Lots of psychic powers, shape changing and general weirdness.
Hideyuki Kikuchi (novel), Roy Szeto, Hark Tsui