Larry Gigli, portrayed by Ben Affleck, is a low-tier mobster in Los Angeles who struggles to embody the tough persona he wishes to project. Instead of being ruthless, he often finds himself letting targets go, even when they pay only a fraction of what they owe. This uncharacteristic leniency earns the ire of his superior, Louis (Lenny Venito), who orders him to abduct the intellectually challenged younger brother of a significant federal prosecutor. The objective is to leverage this hostage to secure the release of mob boss Starkman (Al Pacino) from prison.
To execute the plan, Gigli sets his sights on the young man, Brian, played by Justin Bartha, who lives in a facility for individuals with special needs. Utilizing charm, Gigli lures Brian away by promising an adventure to "the Baywatch," a tempting bait considering Brian's obsession with the famed television series. However, Louis's lack of trust in Gigli’s abilities leads him to hire a woman known as Ricki, played by Jennifer Lopez, to supervise the operation.
Ricki enters Gigli's life under the pretense of a neighbor needing assistance, but quickly reveals her true purpose. Their interactions spark tension as Gigli tries to assert dominance, yet Ricki stands her ground, fiercely protective of Brian. As Gigli grows attracted to Ricki, he grapples with his resentment toward both Louis and the situation, turning to increasingly brazen tactics to impress her, even resorting to seduction attempts that are swiftly rebuffed when Ricki admits being a lesbian.
The plot thickens as Gigli deals with a detective named Stanley Jacobellis (Christopher Walken), who is investigating Brian's disappearance. Faced with mounting pressure, Gigli decides they must hide Brian. Amid familial interactions, Gigli finds himself increasingly frustrated when his mother begins to bond with Ricki, inadvertently pushing him further into emotional turmoil.
As the stakes rise, Gigli and Ricki receive a troubling directive—to sever Brian's thumb and send it to his brother, a horrifying act neither is willing to commit. Matters become dire when Ricki's ex-girlfriend, Robin (Missy Crider), appears, leading to a suspenseful turn of events. In a desperate bid, Gigli resorts to a grim act by sneaking into a morgue to harvest a thumb, which he mistakenly believes will save them.
After a series of harrowing events, Gigli and Ricki confront Starkman, who angrily expresses his disapproval of their plan and its execution. This meeting culminates in a revelation that prompts them to rethink their actions entirely. They ultimately decide to break free from the mob's grip, returning to rescue Brian and help him find his way back home.
Their journey takes a surprising twist as they stumble upon a Baywatch-inspired music video being filmed at the beach, prompting Brian's excitement to be released there. In a moment of redemption, Gigli contacts Brian's brother to guide him towards locating Brian. What follows is a heartwarming conclusion as Gigli persuades Ricki to escape with him, embracing new beginnings together.
