Lethal Weapon is a 1987 American action-comedy film, and the first in the Lethal Weapon series of films, all directed by Richard Donner and starring Mel Gibson and Danny Glover as a mismatched pair of LAPD detectives who are hell bent on protecting and serving despite their differences, and Gary Busey as their primary adversary. After the first film, the series fell into the action-comedy and thriller genres, and is generally considered to typify the "buddy cop" plot device.
Set in December in Los Angeles, LAPD Detective Roger Murtaugh (Danny Glover) is worried about getting old, having recently celebrated his 50th birthday. He receives a message from Michael Hunsaker (Tom Atkins), an old war buddy from his time served during the Vietnam War, whom Murtaugh realizes he has not seen in 12 years. Before he can meet him, he is called to investigate a suicide, and is horrified to find the victim is Amanda Hunsaker, daughter of Michael. Elsewhere, younger L.A.P.D. Detective Martin Riggs (Mel Gibson), who is suicidal following the recent death of his wife in a traffic accident, nearly kills a disarmed suspect after entering a psychotic rage during a drug bust. Weary of his behavior, Riggs' superiors transfer him to Murtaugh's unit, making them very reluctant partners. During Amanda's autopsy, drugs laced with drain cleaner are found in her system. Although she jumped to her death, she would have died within minutes anyway, making her death a homicide. After informing her distraught father, who says he was trying to contact Murtaugh to get Amanda out of her drug and pornography habits, Riggs and Murtaugh go to question a pimp known to have connections to Amanda. Finding a drug lab on the premises, they engage in a brief gunfight with the pimp (who is killed in the process), where Riggs saves Murtaugh's life, leading to respect between them. Having found the drugs and with the pimp dead, Murtaugh assumes the case is closed, but Riggs finds it suspicious that the only witness to Amanda's suicide was a prostitute named Dixie, who was working away from her usual location. They deduce Dixie was the one who poisoned Amanda, then posed as a witness to cover her actions. The next morning, Riggs and Murtaugh go to Dixie's home to question her, but her house explodes just as they arrive. Investigating the site, Riggs, who during the Vietnam War served in US Army Special Forces, finds part of the bomb, a mercury switch, that he knows only a professional would use. A neighborhood child remembers seeing a man at Dixie's earlier, who had a special forces tattoo similar to Riggs' own. Seeing a connection, they decide that Michael Hunsaker knows more than he has admitted and Murtaugh confronts him at Amanda's visitation. Hunsaker admits he is involved in a heroin-smuggling operation run by ex-Vietnam War era special operations troops, known as 'Shadow Company'. The scheme is masterminded by a ruthless retired general, Peter McAllister (Mitchell Ryan) - the former commander of Shadow Company - and his chief enforcer, Mr. Joshua (Gary Busey). Hunsaker was laundering the profits through his bank. McAllister had ordered the murder of Amanda when Michael wanted out and unsuccessfully tried to alert Murtaugh to the scheme. As Murtaugh attempts to make Hunsaker reveal the entirety of his operation, Joshua makes a surprise appearance in a helicopter and shoots Hunsaker dead. As Riggs and Murtaugh attempt to investigate Dixie's connection, the increasingly violent members of Shadow Company attempt to kill Riggs (which they believe is successful, though Riggs had been wearing a bulletproof vest) and then kidnap Murtaugh's daughter Rianne. Using Riggs' presumed-dead status to their advantage, Murtaugh agrees to meet Shadow Company in the desert to exchange himself for Rianne, knowing Shadow Company's plan is to kill them all anyway. As Riggs provides sniper cover from a distance, Roger attempts to make Rianne flee, but ultimately the three are captured. McAllister tortures Murtaugh for information by beating him and rubbing salt into Murtaugh's bullet wound; McAllister demands to know which of their drug shipments have been compromised, eventually threatening Rianne when Murtaugh is not forthcoming, refusing to believe Hunsaker told them nothing. Riggs, brutally tortured with electric shocks, frees himself and then rescues both Murtaugh and Rianne. The pair then fight their way free of their prison, finding themselves in a downtown L.A. nightclub. Riggs chases Joshua on to the street and attempts to cut him off on the freeway, though Joshua ultimately escapes. Murtaugh finds McAllister trying to flee in his car. Taking out McAllister's driver, Murtaugh watches as the car crashes on Hollywood Boulevard and is blown up by a live hand grenade (along with the heroin shipment). Riggs and Murtaugh then head to Murtaugh's home, knowing Joshua will head there to attack Murtaugh's family, who are absent. While Joshua is arrested and led away without incident, Riggs, wanting revenge, proposes "a shot at the title," which Joshua eagerly accepts. Sanctioned by Murtaugh, Riggs engages Joshua in hand-to-hand combat on Murtaugh's front lawn; after a brutal fight, Riggs locks Joshua in the Triangle Chokehold. Riggs releases the pressure and says "You're not worth it" Riggs is the victor. As he's being arrested, Joshua overpowers two officers and attempts to shoot Riggs. Riggs and Murtaugh both draw and fire, killing Joshua. Murtaugh and Riggs are now solid friends, and Riggs spends Christmas Day at the Murtaugh home with Roger's family; Riggs brings his dog Sam to be a friend to the Murtaugh family cat, Burbank (which proves to be disastrous). Riggs also gives Murtaugh a symbolic gift: the unfired bullet which he had been saving to commit suicide, as he does not need it anymore.