Larry Gigli is assigned by a crime boss to kidnap the brother of a prominent district attorney. A beautiful woman known only as Ricki is sent to stay with him to make sure he doesn't mess up the job.
Gigli, a lowly and inept hitman, is assigned a job by the mob to kidnap an intellectually disabled brother of a California district attorney. Gigli abducts the brother from his mental hospital and holds him hostage in his apartment. Ricki, a "lesbian assassin", is sent to oversee Gigli's job and make sure he doesn't screw it up. Comedic high jinks ensue as the two go on the lam and start to fall in love.
A lowly thug, Gigli, is assigned to kidnap the psychologically challenged younger brother of a powerful federal prosecutor to save his mobster boss from incarceration. Staked-out in his one-bedroom apartment with his kidnap victim, Brian, Gigli soon realizes that what he thought would be a routine assignment soon becomes a tumultuous task. Ricki, a gorgeous, free-spirited female gangster is sent to assist Gigli with the kidnapping because his boss does not think that Gigli is up to the job. But when his feelings for the decidedly unavailable Ricki begin to grow, and he actually becomes concerned for Brian, tough guy Gigli begins to transform into an actual human being...which considering his profession could be a very dangerous occupation.
- Larry Gigli (Ben Affleck) is a low-ranking Los Angeles mobster who is not nearly as tough as he likes to act. Louis (Lenny Venito), a higher-ranking member of Gigli's organization, commands Gigli to kidnap the mentally challenged younger brother of a powerful federal prosecutor to use as a bargaining chip to save New York-based mob boss Starkman (Al Pacino) from prison. Gigli successfully convinces the young man, Brian (Justin Bartha), to go off with him by promising to take him "to the Baywatch", apparently a reference to the television show of that name, which seems to be Brian's singular obsession. Louis does not trust Gigli to get the job done right, so he hires a woman calling herself Ricki (Jennifer Lopez) to take charge.
Gigli is attracted to Ricki, but he resents both Louis' lack of faith in him and having to take orders from a woman. He is also frustrated by Brian's insistence on going to "the Baywatch" and by the fact that Ricki is a lesbian. A suspicious detective (Christopher Walken) comes to the apartment to question Gigli in reference to Brian's disappearance. Gigli is further annoyed when his mother (Lainie Kazan) takes an immediate liking to Ricki and when the two women team up to needle him.
The events take a darker turn when Gigli and Ricki receive orders to cut off Brian's thumb, something that neither wants to do. Worse, Ricki's ex-girlfriend, Robin (Missy Crider), shows up at Gigli's apartment, accusing Ricki of changing sexual orientation and attempting suicide by slitting her wrists and is rushed to the hospital, where she thankfully survives. While there, Gigli sneaks into the morgue and cuts off a corpse's thumb, which he sends to the prosecutor as Brian's thumb. Gigli and Ricki go back to Gigli's apartment, where Gigli confesses his love and the two sleep together.
They are summoned to meet with the mob's boss. Starkman reveals that he did not approve of the plan to kidnap a federal prosecutor's brother or the order to cut off Brian's thumb. He nevertheless rages at them because the thumb they sent didn't match Brian's fingerprint, and therefore not only failed to increase pressure on the prosecutor but even undermined the organization's credibility. Starkman then kills Louis, presumably in retaliation for the kidnapping and associated scrutiny by law enforcement. Starkman is about to kill Ricki and Gigli as well, but Ricki talks him out of it by pointing out that only they know where Brian is and only they can silence Brian and prevent him from revealing the involvement of Starkman's organization in the kidnapping or even accusing Starkman of having been personally involved. They leave Starkman's, decide to leave the mob, and discuss taking Brian back to where they found him. On the way, they discover Baywatch (or a similarly themed show or film) shooting an episode on the beach. Brian begs to be let off there and finally they consent.
Gigli convinces Ricki to take his car to escape to parts unknown; but at the last minute, Ricki returns to pick up Gigli, and they leave town together.