During Prohibition, Al Capone (De Niro) has nearly the whole city of Chicago under his control and supplies liquor at high prices. Bureau of Prohibition agent Eliot Ness (Costner), summoned to stop Capone, conducts raids using a large squad of officers. After his efforts fail due to corrupt policemen tipping off Capone, he meets incorruptible Irish American officer Jim Malone (Connery) and is told to enlist men from the police academy who have not yet come under Capone's influence. Italian American trainee George Stone (García), is enlisted due to his superior marksmanship and intelligence. They are joined by accountant Oscar Wallace (Smith), assigned to Ness from Washington, D.C.

Wallace informs Ness that Capone has not filed an income tax return in four years; therefore, they can try Capone for tax evasion. Ness is visited by an alderman who tries to bribe him into dropping the investigation, but Ness throws him out. When Frank Nitti (Drago) threatens Ness's family, Ness has them moved to a safer place, then takes the team to the Canada – United States border for a raid on a liquor shipment. Ness chases one of the gangsters into an empty house and kills him in self-defense. Malone captures George (Sullivan), a Capone bookkeeper, and brings him back to the house for interrogation. George proves uncooperative, so Malone grabs the dead man and shoots him to coerce George into cooperating, much to the dismay of the Royal Canadian Mounted Police who have assisted in the raid.

At the police station, Nitti kills Wallace and George and writes "touchable" on the wall in Wallace's blood. Ness angrily confronts Capone and his men, but Malone intervenes, as Capone mocks Ness over the death of his friend. Malone persuades Ness to stall the district attorney (James) from dropping the case, then corners policeman Mike Dorsett, who sold out Wallace and George to Capone. Malone learns about another Capone accountant, Walter Payne, and calls Ness with the news. A knife-wielding thug breaks into Malone’s home; Malone forces him out the front door with a shotgun, but steps into an ambush set up by Nitti who guns him down with a Tommy gun. He lives long enough for Ness and Stone to find him, and shows them which train Payne will take out of town before he dies.

Ness and Stone arrive at Union Station and find Payne guarded by several gangsters. After a fierce shootout, the two succeed in killing the gangsters and taking Payne alive. Payne testifies in court about the cash flows throughout the Capone organization, with the result of $1 million. Ness, however, notices that Capone seems unperturbed despite the probability of serving a long prison sentence, and also sees Nitti carrying a gun inside his jacket. He escorts Nitti out of the courtroom with the bailiff and discovers that Nitti has the mayor’s permission to carry the weapon. Ness identifies Nitti as Malone’s assassin after seeing Malone's address in Nitti's matchbook.

Nitti shoots the bailiff in a panic and flees to the roof of the building, but Ness corners him. Ness says Nitti will pay for killing Malone, but when Nitti says that he will never go to prison, Ness angrily pushes him off the roof. In the courtroom, Stone shows Ness a document from Nitti’s jacket that reveals that the jury was bribed, explaining Capone's relaxed mood. The judge has no intention of using it as evidence until Ness bluffs that the judge's name is in Payne’s ledger of payoffs. The judge decides to switch juries with a neighboring courtroom and restart the trial. However, Capone's lawyer suddenly withdraws their plea of "not guilty" and enters a plea of "guilty" without Capone's consent, and Capone is sentenced to eleven years in prison.

Packing up his Chicago office, Ness ponders the Saint Jude pendant that Malone had carried with him for many years, and which Malone had given to him before dying. He gives the pendant to Stone, reasoning that Malone would have wanted a cop to have it. A reporter mentions that Prohibition is due to be repealed and asks what Ness might do then, Ness responds, "I think I’ll have a drink."

• Kevin Costner as Eliot Ness
• Sean Connery as Jimmy Malone
• Charles Martin Smith as Oscar Wallace
• Andy García as George Stone
• Robert De Niro as Al Capone
• Patricia Clarkson as Catherine Ness
• Billy Drago as Frank Nitti
• Richard Bradford as Chief Mike Dorsett
• Jack Kehoe as Walter Payne
• Brad Sullivan as George
• Clifton James as District Attorney

De Niro wanted one extra scene written for his character, and time to finish his commitment to the Broadway production of Cuba and His Teddy Bear and to gain about 30 pounds (14 kg) to play Capone; according to De Palma, De Niro was "very concerned about the shape of his face for the part."The Untouchables began production in Chicago on August 18, 1986. Actual historical Chicago locations were featured in the movie.

A month after the film was released, De Palma downplayed his role on the film:

Being a writer myself, I don't like to take credit for things I didn't do. I didn't develop this script. David [Mamet] used some of my ideas and he didn't use some of them. I looked upon it more clinically, as a piece of material that has to be shaped, with certain scenes here or there. But as for the moral dimension, that's more or less the conception of the script, and I just implemented it with my skills – which are well developed. It's good to walk in somebody else's shoes for a while. You get out of your own obsessions; you are in the service of somebody else's vision, and that's a great discipline for a director.

Although De Niro was De Palma's first choice to play Capone, the director met with Bob Hoskins to discuss the role. When De Niro took the part, De Palma mailed Hoskins a check for £20,000 with a "Thank You" note, which prompted Hoskins to call up De Palma and ask him if there were any more movies he didn't want him to be in.

The Untouchables opened on June 3, 1987 in 1,012 theatres where it grossed $10,023,094 on its opening weekend and ranked the sixth-highest opening weekend of 1987. It went on to make $76.2 million in North America. According to producer Art Linson, the polls conducted for the film showed that approximately 50% of the audience was women. "Ordinarily, a violent film attracts predominantly men, but this is also touching, about redemption and relationships and because of that the audience tends to forgive the excesses when it comes to violence".

The Untouchables received positive reviews from film critics and has an 81% rating on Rotten Tomatoes. Vincent Canby, of The New York Times, gave the film a positive review, calling it "a smashing work" and saying it was "vulgar, violent, funny and sometimes breathtakingly beautiful". Conversely, Roger Ebert of the Chicago Sun-Times praised the film for its action sequences and locations. However, Ebert disapproved of David Mamet's script, as well as Brian De Palma's direction Hal Hinson, in his review for the Washington Post, criticized De Palma's direction: "And somehow we're put off here by the spectacular stuff he throws up onto the screen. De Palma's storytelling instincts have given way completely to his interest in film as a visual medium. His only real concern is his own style".Time magazine's Richard Schickel wrote, "Mamet's elegantly efficient script does not waste a word, and De Palma does not waste a shot. The result is a densely layered work moving with confident, compulsive energy".

Ebert singled out De Niro's scenes portraying Al Capone as the biggest disappointment of the film, while giving praise to Sean Connery's work. While he was voted first place in an Empire magazine historical poll for worst film accent, Connery was awarded the 1987 Academy Award for Best Actor in a Supporting Role for his performance. Pauline Kael called it "a great audience movie – a wonderful potboiler." Time magazine ranked it as one of the best films of 1987.

Academy Awards

Award	Person
Won:
Best Actor in a Supporting Role	Sean Connery
Nominated:
Best Costume Design	Marilyn Vance
Best Score	Ennio Morricone
Best Art Direction - Set Decoration	Patrizia von Brandenstein William A. Elliott Hal Gausman

American Film Institute

• AFI's 100 Years...100 Movies – Nominated
• AFI's 100 Years...100 Thrills – Nominated
• AFI's 100 Years...100 Heroes and Villains:
  • Al Capone – Nominated (Villain)
  • Eliot Ness – Nominated (Hero)
• AFI's 100 Years of Film Scores – Nominated
• AFI's 10 Top 10 – Nominated (Gangster Film)

A side-scrolling video game was released by Ocean Software in 1989 on ZX Spectrum, Amstrad CPC, Commodore 64, MSX, Amiga, DOS, and later on NES, and SNES. Based loosely on the movie, the game plays out some of the more significant parts of the film. Set in Chicago, the primary goal of the game is to take down Al Capone's henchmen and eventually detain Capone.

• The Untouchables (1957 book)
• The Untouchables (1959 TV series)
• The Untouchables (1993 TV series)