Veteran inspector Cheng Biu (Bill Tung) is killed during a drug bust. Mistakenly ruled a suicide, his restless spirit is sent back by heaven to find his “saviour,” rookie cop Sing (Stephen Chow). In exchange for getting Biu justice, Sing must also nab a promotion and win a romance with his partner’s daughter. As ghost and rookie team up—using Taoist spells, slapstick antics, and supernatural detective work—they pursue the ruthless drug lord Teng Lee-Yang (Sunny Fang) and uncover the truth behind Biu’s death