Set approximately two years after the original film, Captain Bogomil (Ronny Cox), Billy Rosewood (Judge Reinhold), and John Taggart (John Ashton) are trying to figure out who is behind the "Alphabet Crimes", a series of mostly high end store robberies (and one shooting) distinctive by their monogrammed envelopes with an alphabetical sequence the assailants leave behind. Complicating matters is the new "political" state of the Beverly Hills police, headed by temperamental new police chief Harold Lutz (Allen Garfield), doing everything he can to stay on the Mayors good side.

While investigating a lead, Bogomil is shot by Karla Fry (Brigitte Nielsen), the chief hench woman of Maxwell Dent (Jürgen Prochnow). Finding out about the shooting over a news report, Axel (Murphy) immediately flies out to Beverly Hills (covering his absence from his actual job in Detroit by telling his commanding officer he was going "deep deep deep DEEP undercover" on the credit card fraud case he had been assigned to) to help find out who shot Bogomil and why. Posing as an undercover FBI agent to get past Lutz, Axel soon starts making the connection between the robberies and Dent, who is financing his gun trade to Central America. Having foiled a robbery attempt at a bank depository, Axel soon uncovers that Dent is planning on making his getaway. Axel, Billy and Taggert track Dent to where he's making his final arms deal and take everyone down, including Dent and Karla.