Three grisly murders has shaken up the police department in Taipei. The victims are unrelated, but the coroner (Yang Kwei Mei) finds a mysterious black fungus in their brains, along with evidence that they had all died in a hallucinatory state. With the public on the verge of panic, the high command grudgingly calls on the country's closest ally -- the United States -- for help and the FBI sends its top expert, Kevin Richter (David Morse) to work with ace detective Huang Huo Tu (Tony Leung Ka Fai)...