Miles Logan (MARTIN LAWRENCE) is a high-tech jewel thief who's after a multimillion dollar diamond. Although he successfully extracts it, his turncoat partner, Deacon (PETER GREENE), kills another member of their team. That sends their driver, Tulley (DAVE CHAPPELLE), speeding away and results in Logan's arrest, but not before he stashes the diamond in a building that's under construction.
Two years later, Logan's released from jail and discovers to his horror that his diamond is now located in the recently completed L.A.P.D. precinct building. Desperate to retrieve it, and with the aid of a master forger, Uncle Lou (RICHARD C. SARAFIAN), Logan poses as a detective and gains access to the building.
Yet in his attempt to find the diamond, Logan inadvertently catches an escaped suspect, drawing the attention of Captain Rizzo (GRAHAM BECKEL). Impressed by Logan's style and faked credentials, Rizzo partners him with Carlson (LUKE WILSON), a green around the edges, rookie detective. After similarly arresting Tulley -- who threatens to blow Logan's cover -- the ex-con soon finds himself promoted to head detective, where he continues to impress other cops such as seasoned pro, Hardcastle (WILLIAM FORSYTHE).
As Logan's intimate knowledge of everything criminal turns him into a proficient detective who's always two steps ahead of the criminals, his quest to retrieve the diamond soon gets him tangled up in other cases and with the FBI.