Plot

The McCallister family is preparing to spend Christmas in Paris, gathering at Peter (John Heard) and Kate's home (Catherine O'Hara) in a Chicago suburb on the night before their departure. Peter and Kate's youngest son, Kevin (Macaulay Culkin), is the subject of ridicule by his older siblings. Later, Kevin accidentally ruins the family dinner (when he attacks Buzz for eating his plain cheese pizza) and their flight tickets to Paris (the scuffle pours Pepsi all over the tickets and the passport) after a scuffle with his older brother Buzz (Devin Ratray), resulting in him getting sent to the attic of the house as a punishment, where he berates Kate and wishes that his family would disappear.

Family includes Kevin's older sister Linnie (Angela Goethals), Jeff (Michael C. Maronna), Kevin's older brother and oldest sister Megan (Hillary Wolf). Uncle Frank (Gerry Bamman), Peter's rude older brother and Aunt Leslie (Terrie Snell). Heather (Kristin Minter), Kevin's oldest cousin. Sondra (Daiana Campeanu), Kevin's older cousin. Rod (Jedidiah Cohen), Kevin's older cousin. Fuller (Kieran Culkin), Kevin's youngest cousin. Tracy (Senta Moses), Kevin's older cousin. Brook (Anna Slotky), Kevin's younger cousin. Steffan (Matt Doherty), Kevin's older cousin. Uncle Rob (Ray Toler), Kevin's uncle, younger brother of Peter and Uncle Frank, and father of Heather and Steffan. Georgette (Virginia Smith), Kevin's aunt.

During the night, heavy winds damage the power lines, which causes a power outage and resets the alarm clocks, causing the family to oversleep. In the confusion and rush to get to the airport, Kevin is accidentally left behind (Mitch Murphy (Jeffrey Wiseman), an eight-year-old neighbor of the McCallisters whom Heather mistakes for Kevin during the headcount).

Kevin wakes to find the house empty and, thinking that his wish has come true, is overjoyed with his newfound freedom (Jumping on parent's bed, buzz's playboys, watching R rated movies, destroys Buzz's shelf and releases his tarantula). However, he soon becomes frightened by his next door neighbor, Old Man Marley (Roberts Blossom), who is rumored to be a serial killer who murdered his own family in 1958, as well as the "Wet Bandits", Harry (Joe Pesci) and Marv (Daniel Stern), a pair of burglars who have been breaking into other vacant houses in the neighborhood and have targeted the McCallisters' house (They cased it the night before they left (posing as cops) and figured the entire family is gone for the holidays to France). Kevin tricks them into thinking that his family is still home, forcing them to put their plans on hold (the first night Kevin turns the basement light on).

Kate realizes mid-flight that Kevin was left behind, and upon arrival in Paris, the family discovers that all flights for the next two days are booked. Kate tries to call home, but the phone lines are down. She calls the police, who send an officer home, but Kevin thinks it's the robbers again and hides under the bed. The police think no-one is home. Peter and the rest of the family stay in his brother's apartment in Paris, while Kate manages to get a flight back to the United States (Dallas), but only gets as far as Scranton, Pennsylvania. She attempts to book a flight to Chicago, but again, everything is booked. Unable to accept this, Kate is overheard by Gus Polinski (John Candy), the lead member of a traveling polka band, who offers to let her travel with them to Chicago on their way to Milwaukee in a moving van, which she gratefully accepts.

Meanwhile, Harry and Marv finally realize that Kevin is home alone (Harry and Marv hear Peter's message on the answering machine in the house next door they are robbing and are again convinced that Kevin's house is empty. That day Harry and Marv run into Kevin while he is shopping and follow him. Kevin hides in a church and that night preps cardboard cutouts in his house that give the impression (from the window) that there is a big party on inside), and on Christmas Eve, Kevin overhears them discussing plans to break into his house that night (harry and Marv had stayed outside the house all night and founds no one came or went, except Kevin in the morning).

Kevin starts to miss his family and asks the local Santa Claus impersonator if he could bring his family back for Christmas. He goes to church and watches a choir perform, then meets Old Man Marley, who dispels the rumors about him. He points out his granddaughter in the choir, whom he never gets to meet, as he and his son are estranged; Kevin suggests that he should reconcile with his son.

Kevin returns home and rigs the house with booby traps to take on the burglars. Harry and Marv break in at 9 pm, spring the traps, and suffer various injuries. Harry and Marv try the back door, where Kevin shoots them through the kitty door in the Nards and angers them off.

Harry attacks the front door and Marv the basement. Kevin had iced the front porch and hung a heater around the doorknob, blow torch that ignites when the door is opened, glue and feathers rigged to a fan, with Buzz's toy cars at the entrance. Kevin has also iced the basement entrance, hot iron rigged to a light bulb switch, big nails on tar on the basement steps. Marv tries to enter via a window and steps on Christmas ornaments. Full paint cans a lead pipe on the staircase. The tarantula plays its part, by scaring Marv and getting him to hit Harry with a pipe (while he was trying get the spider).

While the duo pursues Kevin around the house, he calls the police and flees, then lures Harry and Marv into a neighboring home which they previously broke into. They ambush him and prepare to get their revenge, but Marley intervenes and knocks them unconscious with his snow shovel. The police arrive and arrest Harry and Marv, having identified all the houses that they broke into due to Marv's destructive characteristic of flooding them.

On Christmas Day, Kevin is disappointed to find that his family is still gone. He then hears Kate enter the house and call for him; they reconcile and are soon joined by Peter, Buzz, Jeff, Megan, and Linnie, who waited in Paris until they could obtain a direct flight to Chicago. Kevin keeps silent about his encounter with Harry and Marv, although Peter finds Harry's knocked-out gold tooth. Kevin then observes Marley reuniting with his son, daughter-in-law, and granddaughter. Marley notices Kevin, and the pair wave to each other.