This movie has numerous characters and subplots, most of which are tied together at one point or another.
1) Howard Finnigan, a TV news commentator (Bruce Davison) and his wife Ann (Andie McDowell) are preparing for a birthday party for their young son son Casey. Waitress Doreen Piggot (Lily Tomlin) hits Casey with her car. The boy gets up and walks away, appearing to be fine. But when he gets home, he falls into a severe coma.
The baker (Lyle Lovett) who had been making a birthday cake for Casey’s party tries to call Ann, but she is so distraught by her son’s injuries that she blows him off. The baker becomes angry, and starts making a series of threatening and obscene phone calls to Ann.
Howard’s long-estranged father Paul (Jack Lemmon) shows up at the hospital to see Casey and console his son. He finally gets the courage to tell Howard why he abandoned the family years ago: he had been seduced by his sister-in-law. When his wife, Howard’s mother, found out, she ordered Paul to leave forever.
Ultimately, Casey dies. Sadly, Paul leaves the hospital, probably never to see his son again. The grieving Ann goes to the bakery and confronts the baker. She tells him about her dead son, and then breaks down. The baker, ashamed of himself, begins treating Ann kindly and sympathetically.
2) Stuart Kane (Fred Ward) goes on a weekend camping/fishing trip with his friends. As soon as they arrive at the lake, they find a dead naked girl in the water. They decide that calling the police would ruin the trip, so they carry on fishing, drinking beer and having fun for a few days before they finally notify the authorities. When Stuart comes home and tells his wife Claire (Anne Archer) what happened, she is horrified and disgusted by her husband’s callousness. She later attends the dead girl’s funeral, because she feels so guilty about her husband’s inaction.
Meanwhile, Dr. Ralph Wyman (Matthew Modine) confronts his artist wife Marian (Julianne Moore) about an affair he suspects she’s been having. He makes his accusations just as she has taken off her pants, and is standing before him with her private parts exposed. She is forced to admit that she did have sex with another man, but tries to reassure him that the other man never ejaculated inside her.
Stuart and Clare had planned to spend an evening with Ralph and Marian. Both couples drink heavily throughout the evening, with Claire making constant hints about Stuart’s callousness and Ralph’s making constant allusions to Marian’s infidelity.
3) Helicopter pilot Stormy Weathers (Peter Gallagher) is furious at his adulterous wife Betty (Frances McDormand), who’s in the process of divorcing him. Stormy breaks into their house during the day and spends hours cutting all her clothes and all her other possessions in half.
4) Depressed cellist Zoe (Lori Singer), daughter of alcoholic lounge singer Tess Trainer, commits suicide by starting her car engine and breathing in the toxic fumes.
5) Jerry Kaiser (Chris Penn) and his friend Bill Bush (Robert Downey Jr.) wander off from a family picnic in the park, and try to pick up some girls they meet. They split up, until Bill hears screams. He runs back to find Jerry beating one of the girls to death. At this moment, one of Los Angeles’ common earthquakes occurs. The girl’s death is blamed upon the earthquake, and Jerry gets away scot-free (was he also the one who killed the girl we saw earlier in the lake?).
6) As the earthquake strikes, Doreen is feeling happy and exhilarated, since she believes wrongly that the boy he hit with her car is okay. She and her drunk limo driver husband (Tom Waits) are gleefully making out as the earthquake hits.
At the very end of the movie, Stormy Weathers is interviewed on TV about the earthquake. He observes that only one person died, and cheerfully says everyone should feel lucky to live in L.A.
Thanks John L!