Mona Dearly (Bette Midler) leaves her home and tries in vain to unlock her car. Her keys fit her son's Yugo, however, so she takes that and drives off. In a bend, the brakes fail completely and she drives off a cliff into the Hudson River. Clarence (Tracey Walter), fishing in the river, sees it happen. Chief Wyatt Rash (Danny DeVito) later observes that there are no skid marks on the road.
Her long-suffering husband Phil (William Fichtner) and son, Jeph (Marcus Thomas), evince no particular grief when they learn of the death of Mona, an abusive, belligerent heavy drinker, loved by none. (Jeph is more concerned about his car.)
Ellie Rash (Neve Campbell) (Wyatt's daughter) wants to celebrate because she feels the Dearlys treated Bobby (Casey Affleck), her fiancé and Jeph's business partner, badly. JB Landscaping is not doing well due to Jeph's laziness and poor behavior.
Phil and Rona (Jamie Lee Curtis), who are having an affair, meet at the Charm Motel. Phil expresses his happiness about Mona's death but denies involvement. Bobby meets Murph (Mark Pellegrino), his older brother. Due to his financial difficulties, Bobby has been receiving money from Murph, who thinks he had a hand in Mona's death.
Wyatt's investigation takes him to Jeph, who claims that Bobby threatened and attacked Mona. Lucinda (Kathleen Wilhoite), the local mechanic specializing in Yugos (which everyone in town drives) informs Wyatt that the car Mona was driving had been tampered with in multiple ways.
Phil tells Wyatt that he had been a battered husband since Mona suspected he was having an affair. He also claims Jeph and Mona had had an argument on the evening before the accident. Bobby tells Wyatt that he hated Mona and that they had had an argument over Jeph's pay. Mona would not let him dissolve the partnership unless Bobby bought them out. Phil and Jeph leave Mona's wake very early.
Meanwhile, Wyatt breaks into the Dearly house and finds that Mona's and Jeph's car keys had been switched. Phil expresses his gratitude to Bobby for killing Mona. Bobby then confesses to Ellie that he rigged Jeph's car, because Jeph was destroying their business. Ellie then announces that she is pregnant. This conversation is overheard by Clarence.
Phil tells Wyatt that he spotted Bobby near the Dearly residence on the night prior to the accident, claiming that he did not say this earlier because Wyatt and Bobby are soon to be family. Jeph, who it turns out is also involved with Rona, finds out about Phil's affair with her. Bobby tells Wyatt that Mona threatened him, not the other way around, and that he was in the Hideaway the evening before the accident, which, as Valerie[who?] tells Wyatt, is not true. Murph later tries to cover Bobby on this. Valerie also gives him a sharp gardening tool with the letters "JB" on it.
Phil is discovered dead in a pond at the Charm Motel. Murph tells this to Ellie, who fears that Bobby, who left their house that night, has killed again. When Rona finds out, she tries to leave town. It turns out Jeph did not help Phil when he fell into the water after Phil threatened Jeph that he was going to expose him, Rona, and Bobby.
Police learn that Jeph is threatening suicide because of Rona's leaving. Jeph reveals that a drunken Mona had, accidentally but unrepentantly, chopped off his right hand when they fought over a bottle of beer. He also states that Phil was not his biological father, adding that, despite all that, he did not kill either of them. Wyatt manages to take the gun away from Jeph.
Wyatt then tells Bobby in private that Clarence confessed to killing Phil, because he could not stand the idea of Bobby going to jail, especially with the baby on the way. It turns out that Clarence was watching Phil - who had seen Bobby rig the car - tampering with it some more and then switching the keys in the house. The initial tampering by Bobby had been superficial and did not contribute to the accident, whereas Phil's did.
Wyatt promises Bobby to keep quiet about Bobby's involvement as long as he takes good care of Ellie and the baby. Finally, Bobby and Ellie get married and Clarence gets taken away.
Danny DeVito as Chief Wyatt Rash
Bette Midler as Mona Dearly
Neve Campbell as Ellen "Ellie" Rash
Jamie Lee Curtis as Rona Mace
Casey Affleck as Bobby Calzone
William Fichtner as Phil Dearly
Marcus Thomas as Jeph Dearly
Peter Dobson as Lt. Feege Gruber
Kathleen Wilhoite as Lucinda
Mark Pellegrino as Murph Calzone
Tracey Walter as Clarence
Will Ferrell as Cubby, the Funeral Director
Paul Ben-Victor as Deputy Tony Carlucci
Paul Schulze as Deputy Jimmy D.
Melissa McCarthy as Shirley
Brian Doyle-Murray as Tow Truck Driver
Raymond O'Connor as Father Tom
Lisa Rieffel as Valerie