Plot
L.A.P.D. Sergeants Martin Riggs and Roger Murtaugh engage in a car chase with other L.A.P.D. detectives. When their objective crashes, Riggs and Murtaugh search the abandoned car and discover the trunk is full of gold Krugerrands (illegal to import into the U.S. at that time), leading to the conclusion that the criminals in the pursuit are from Apartheid South Africa. Later that night, Arjen Rudd (Joss Ackland), the minister of affairs for the South African Consulate, orders his head of security Pieter Vorstedt (Derrick O'Connor) to warn Murtaugh and Trish at his home to cease the investigation around the Krugerrands. They do so, and in the wake of the attack on Murtaugh and his family, he and Riggs are reassigned to protecting a federal witness, Leo Getz (Joe Pesci), a loudmouthed accountant who decided to blow the whistle on his money laundering clients. A running gag in the film involves Murtaugh's daughter, who has appeared in a TV advertisement for condoms, embarrassing Murtaugh amongst his work colleagues.
　
Mere moments after arriving at Getz's hotel room, an assassin posing as room service enters the room and tries to kill Getz. After falling out of the window into the hotel pool, Riggs and Murtaugh save Getz and discover he formerly laundered funds for the same drug smugglers. Getz leads them to the smugglers' base of operations, a house on stilts. Riggs recognizes the assassin from the hotel, who then tries to make an escape by stealing a tow-truck parked outside the house. Riggs jumps onto the back of the tow truck, and Murtaugh and Getz chase after Riggs and the suspect. Later that day, Riggs and Murtaugh return to the house with full backup from detectives and uniformed officers. Attempting to arrest the gang, Riggs and Murtaugh are confronted by Arjen Rudd and members of the South African Consulate. Vorstedt recognizes Riggs but before he can go any further, Rudd invokes diplomatic immunity on behalf of himself and his "staff," halting the action: "My dear officer, you could not even give me a parking ticket."
　
Although ordered to leave Rudd and his associates alone, Riggs infiltrates the consulate building while Murtaugh creates a distraction and catches the name "Alba Varden," a name that appears familiar to Murtaugh. At the same time, Riggs begins to openly harass Rudd, and also begins a romance with Rudd's secretary, Rika van den Haas (Patsy Kensit), who strongly dislikes both her boss and her country's policies. Riggs invites her to a dinner at his trailer and they end up sleeping together.
　
Fed up with Riggs, Rudd orders Vorstedt to brutally murder the L.A.P.D. detectives investigating them. While guarding Getz, Murtaugh views an old birthday video and learns that Alba Varden is the name of a ship currently at the docks. He realizes that Rudd is planning to use the ship to smuggle his billions in drug money to Cape Town. At the same time Getz is kidnapped from Murtaugh's unguarded car, and Murtaugh is attacked by two of Vorstedt's men but manages to thwart them with a nail gun. On their part, Riggs and Rika manage to escape an attack in which Riggs' trailer is shot up by Rudd's men via machineguns from two helicopters. When he returns Rika to her house, he is knocked out and captured by Vorstedt. Vorstedt confesses to murdering Riggs's wife years ago by mistake, intending to kill Riggs when he had gotten too close to their drug operation, and drops him into the Los Angeles harbor in a straitjacket to drown. Riggs escapes by dislocating his shoulder (an ability displayed earlier in a scene with his police colleagues), but finds Rika nearby, drowned in the same fashion. Vengefully, Riggs calls Murtaugh and announces that he is going after Vorstedt and Rudd. Leaving his own badge at the station, Murtaugh leaves to help him kill Vorstedt and Rudd.
　
Meeting at Rudd's stilt house, Murtaugh heads inside to rescue Getz. Meanwhile, Riggs uses his truck to dislocate the stilts, causing the house to collapse just as Getz and Murtaugh escape. Because Murtaugh learned that the Alba Varden will leave for South Africa the next day, the sergeants go to the dock where the freighter is moored. They enter a cargo container and discover it is filled with millions in Rudd's drug money. When they are discovered and the cargo container is sealed, they use a Mercedes within the container to bust their way out. Riggs and Murtaugh rappel down ropes onto the deck of the Alba Varden, engaging the crew in a firefight and killing them one by one.
　
Eventually, Riggs runs into Vorstedt, and they engage in a brutal hand-to-hand showdown, which ends with Riggs dropping a cargo container on Vorstedt, crushing him. Rudd appears from a balcony on the Alba Varden behind Riggs and shoots him before Murtaugh draws his gun and attempts to arrest the diplomat. Rudd holds up his ID and gloats, "Diplomatic immunity." Murtaugh shoots him in the head, replying: "It's just been revoked!", and afterwards tends to Riggs while the L.A.P.D. arrives.
　
Box office performance
Lethal Weapon 2 was the third most successful film of 1989 in North America (after Batman and Indiana Jones and the Last Crusade), earning nearly $150 million domestically and $80.6 million overseas.
　
Critical reception
The film received mostly positive reviews, although not as many as the original. It currently holds an 83% approval on Rotten Tomatoes based on 36 reviews with an average rating of 6.6/10. Despite being an overtly anti-Apartheid film and being dismissed by the then South African Consul General in Los Angeles as "an awful film", Lethal Weapon 2 was released uncut in South Africa and was a box-office success.
　
Mel Gibson, Danny Glover, and Richard Donner have all stated that this is their favorite film of the Lethal Weapon series.