At a dinner party at the Carvers' house, the adults discuss pop culture references that defined the 1970s: the Watergate scandal, swinging parties for married couples, and the pornographic film ''Deep Throat''. The Hood family includes Ben, Elena, and their children, 16-year-old Paul and 14-year-old Wendy. Their neighbors, the Carvers, include Jim, Janey, and their children: Mikey and Sandy.
Ben, dissatisfied in his marriage and with the futility of his career, is having an affair with Janey. Elena is bored with her life and is looking to expand her thinking but is unsure of how to do so. Wendy enjoys sexual games with her school peers. Paul, an occasional drug user, is trying to bed his schoolmate Libbets Casey. Jim's sons are lonely and confused: Mikey plays along with Wendy's sexual games, while Sandy, obsessed with violence, also is attracted to Wendy.
Jim travels for his job and is, for the most part, not involved in his children's lives. In one scene he returns from a trip to find that his sons had not even realized he had been gone. Janey, who appears to be carrying on with a number of other men in addition to Ben, finds Jim to be largely an annoyance and would prefer he remain gone all the time. Elena buys spiritual and self-help books and becomes friendly with the hippie-ish minister of a local church. She is ultimately turned off by his subtle passes and his patronizing behavior towards her. Later she attempts to shoplift, but is caught in the act.
During their trysts, Ben obsesses to Janey over his displeasure with his job and his frustrations at continually being bested by his colleague, smarmy George Clair. Janey seems to have become bored with the arrangement since she has now become unfaithful, not only to her husband but to Ben as well. She abruptly leaves the room just prior to a planned sexual encounter with Ben, excusing herself to get "birth control" but instead flees the house leaving Ben alone.
Realizing that she is not returning, Ben prepares to leave but comes upon his daughter Wendy in the Carvers' basement initiating a sex act with Mikey (a few days previously, she had revealed her genitalia to Sandy). Ben then has an awkward discussion with Wendy about sex. Wendy is visibly bored with the conversation. Seeing this, he changes tack and tells her he's really not all that upset with her, except that he thinks that Mikey may not "be right" for her.
As the evening begins, a storm hits New Canaan which evolves into a dangerous ice storm.
When Ben reveals to Elena that he found Wendy in the Carvers' basement, she is more concerned with what ''he'' was doing there, eventually concluding (correctly) that he must be having an affair with Janey. They have a brief argument over it prior to attending a neighborhood party, which turns out to be a swinger's key party. Elena suspects that Ben was aware of the nature of the party and had plotted to mark his keys so Janey could fish them out. In her resentment, she decides to participate in the key party.
Concurrently, Paul has taken the train into Manhattan. Paul is excited that Libbets has invited him to visit her that evening. He tries to keep this a secret from his roommate, Francis (of whom he is not particularly fond), since he has the habit of bedding every girl he discovers Paul is attracted to. Paul is then disheartened to discover Francis has also been invited. The three listen to music and begin drinking and smoking marijuana. It becomes clear that Libbets is more responsive to Francis' direct advances than to Paul's subtler ones. Paul attempts to drug Francis with Libbets' mother's sleeping medication so that he will be out of commission for the evening, but Libbets also takes one of the pills. Francis passes out first. Libbets and Paul leave him to sleep it off on the floor and Paul tries to make his move on Libbets. He is visibly disappointed when she tells him that she only thinks of him "like a brother" before she too passes out.
Wendy decides to make her way to the Carvers' to see Mikey, but he has decided to go out into the ice storm, so she and Sandy climb into bed together and remove their clothes. They drink from a bottle of vodka and Wendy tries to seduce him; however, they both fall asleep.
As the key party progresses, Ben becomes drunk. When Janey chooses the keys of a handsome young man, Ben attempts to protest but trips and knocks his head on the coffee table, leading Jim to realize that his wife and Ben are having an affair. Ben, in his embarrassment, retreats to the bathroom where he remains for the rest of the evening. The remaining key party participants are paired off and leave together with only Jim and Elena remaining. She retrieves Jim's keys from the bowl and returns them to him. After debating the issue, Jim and Elena leave together, engaging in a quick, clumsy sexual encounter in the front seat of Jim's car. Jim, regretting the line he and Elena have just crossed, agrees to drive her home.
Meanwhile, Mikey, out walking in the storm, is enchanted by the beauty of the trees and fields covered in ice. He slides down an icy hill then sits on a guardrail to rest. A moment later a power line, broken by a fallen tree, connects with the guardrail and he is electrocuted.
Jim and Elena return to the Carvers' house as dawn is breaking. Elena walks in on her daughter in bed with Sandy and orders her to get dressed.
Janey had also returned home earlier and curled up on her bed in the fetal position without bothering to take off her party clothes. Although it is not revealed what transpired between Janey and her 'key partner', she is visibly exhausted and sad.
Ben has sobered up by this time and begins driving home. He discovers Mikey's body on the side of the road and carries it back to the Carvers' house. The two families are drawn together by Mikey's death and Wendy hugs the shocked and numbed Sandy in an attempt to comfort him. Jim is devastated while Janey remains asleep and ignorant to the recent events. Ben, Elena and Wendy then drive to the train station to pick up Paul who is returning from Libbets' apartment, his train delayed by the ice and the power failure caused by the downed wire. Once all four are together in the car, Ben breaks down, sobbing uncontrollably at the wheel as Elena starts comforting him.
This article uses material from the Wikipedia article "The_Ice_Storm_(film)", which is released under the Creative Commons Attribution-Share-Alike License 3.0