Kevin McCallister is a young eight-year-old boy who is mistakenly left at home by his family when they were going on vacation for Christmas. He is often bullied by his older siblings. He lives with his parents, older siblings, uncle, aunt, and cousin. Not much information is known about his background.
After getting into an argument with his older brother Buzz because he ate Kevin's cheese pizza on purpose, Kevin is sent to the third floor of the house by his mother Kate, and wishes his family would disappear. After a power surge that reset their alarm, the McCallisters wake up four hours late and rush to get to the airport. Kevin, who is apparently still sleeping, is left behind in bed. When Heather does a headcount to make sure everybody is there, a neighbor boy named Mitch Murphy, who also leaves for vacation to Orlando, Florida, is mistaken for Kevin. So the family leaves for the airport, and Kevin wakes up to find his whole entire family gone. Kevin is overjoyed that his wish had came true. He gets away with taking Buzz's life savings (which he uses later to buy food), practicing shooting Buzz's BB gun, jumping on the bed, and watching a gangster film while eating ice cream. His mother send the police over to the house to check on Kevin, which also cause Kevin to be frightened as well.
On Christmas Eve, Kevin overhears the plans of the Wet Bandits, composed of two robbers, Harry and Marv, known for robbing houses when the families leave for vacation. He sets a series of booby traps after talking with Old Man Marley. The robbers, who were initially fooled by Kevin into thinking that his family is at home, realized that Kevin was the one home alone and make their move. After making the robbers go through a series of traps, Kevin calls 9-1-1 from his parents room, and is soon trapped by the robbers who plan to bite off all his fingers one by one. Marley later knocks them out with a snow shovel and takes Kevin back home. The next morning, Kevin wakes up to find that his mother has returned. Then the rest of the McCallisters return some minutes later. Buzz reconciles with Kevin, telling him he thought it was pretty cool that Kevin didn't burn the house down, and Kevin thanks him. Later Buzz interrupts Kevin's musings while watching Old Man Marley reunite with his family by calling out, "Kevin! What did you do to my room?!"
In Home Alone 2: Lost In New York Kevin is now 10 years old. After Buzz humiliates Kevin during his solo in front of the whole audience, Kevin punchesBuzz in the stomach, which knocks over the other children as well, which sends the cardboard Christmas tree crashing down on the pianist. That night, Buzz "apologizes" to Kevin and the rest of the family, but Kevin refuses to apologize to Buzz because he had still been a jerk to Kevin, without the family knowing and goes up to the third floor; he also reiterates his disgust with the family's decision to go to Florida for the holidays. After berating Kate, he wishes that he could go on his own vacation by himself and have the best time of his life, to which Kate reminds Kevin that his wish to be home alone came true the previous year, so his vacation wish might come true this time, to which Kevin replies in an angry, agitated tone, "I hope so!"
The day of the flight the McCallisters sleep in (because of Peter accidentally unplugging the radio clock the night before) and rush through the airport to make their flight, and Kevin stops while getting batteries for his Talkboy. Seeing a man who is wearing the same color coat as Peter, he follows him toward a flight on a Boeing 767 to LaGuardia Airport in New York City. Kevin ends up in New York with his father's travel bag and wallet, while his family and his luggage arrive in Miami; when the family realizes Kevin did not make the trip to Miami, Kate faints.
While contemplating on a place to stay while in New York, Kevin walks through Central Park and meets a lady that is covered in rags and tends to pigeons, which makes him shudder. He spots the Plaza Hotel, which he had heard mentioned on a game show the night before, and checks in pretending to be on vacation with his father, using Peter's credit card from his wallet. While at the hotel, Kevin goes on a tour of New York in a white limo and ends up at Duncan's Toy Chest, and meets the philanthropist owner, Mr. Duncan, who tells him the proceeds from the store's Christmas sales will go to children's hospitals. After Kevin donates some money, Mr. Duncan allows him take a pair of ceramic turtledoves, instructing him to give one to someone else as a symbol of friendship. Kevin leaves the store and runs into Harry and Marv. He flees to the Plaza, but the Plaza's concierge Mr. Hector (Tim Curry) has investigated Kevin's suspicious cover story and believes Peter's credit card to be stolen. Kevin manages to flee the hotel staff, but is kidnapped by Marv and Harry. The two plan to get their revenge on Kevin for sending them to prison in the previous film. Then Marv mentions their plan to rob the toy store, which Kevin tape records before goosing the lady Marv met the day before, making her strike both Harry and Marv in the process and allowing Kevin to escape into the back of a hansom cab.
Using his father's address book, Kevin finds the home of his Uncle Rob, but the door is locked and the home is being renovated, as Uncle Rob and his wife are still living abroad in Paris. Kevin wanders the streets and encounters the pigeon lady again, and attempts to run but gets his foot caught. She frees him and Kevin apologizes for being scared of her. The two watch a Christmas concert in a loft above Carnegie Hall, where the pigeon lady tells Kevin about how her life has fallen apart and how she dealt with it by taking care of the pigeons in the park, leading to her current distraught and homeless state. He promises to be her friend if she needs one, and she smiles. Then while walking the streets, Kevin stops at the children's hospital and waves to a sick child, giving him a look of compassion. Remembering what both Mr. Duncan and Marv said, Kevin decides to stop the bandits from robbing the store and rushes back to Uncle Rob's home. There, Kevin uses the renovation materials to set up a series of booby-traps throughout the home.
Kevin arrives at the toy store in the middle of the heist, makes a seesaw using a board and bucket, photographs the two in the process of the crime and finally sets off the store's alarm by throwing a rock tied with a note to Mr. Duncan through the store's window, shattering it. Harry then runs out to the window and steps on one end of the seesaw, but before he can warn Marv not to step on the other end, Marv does exactly that and sends Harry flying into the air, causing him to painfully land on the roof of a parked car. Harry and Marv then chase Kevin to Uncle Rob's house, break into the home, and are beset by Kevin's brutal booby-traps before finally falling from a rope lit on fire, as Kevin calls the police from a phone booth.
The bandits catch him, but the pigeon lady enters the scene and douses the two with bird seed, prompting pigeons to swoop down and swarm them. Kevin runs and sets off fireworks, which he bought earlier, to signal the police, who arrest the bandits and have Kevin's photographs and tape recording to use as evidence against them. At the toy store, Mr. Duncan finds Kevin's note and realizes his role in stopping the bandits.
Kate is looking for Kevin in Times Square, and informs two police officers. While talking to them, she mentions (and remembers) Kevin's fondness for Christmas trees, and asks them for a ride to Rockefeller Center. Her intuition proves correct, as she then finds Kevin in front of the Rockefeller Center Christmas tree, and the two embrace and apologize to each other (a parallel to the first movie's mother-and-son reconciliation scene) before heading back to the Plaza.
A truckload of gifts comes to the Plaza the next morning as a reward for Kevin's foiling of the robbery, and Buzz suggests that had it not been for Kevin getting on the wrong flight, they would not be in the suite with the Christmas tree and gifts in the first place. So, he decides to allow Kevin to open up the first present as a sign of reconciliation. While everyone else is opening their presents, Kevin runs out into the snow to give the pigeon lady one of the two turtledoves Mr. Duncan gave him and reaffirms his promise to be her friend, and they hug. Meanwhile, Kevin's room service bill from his original stay at the hotel is delivered to the suite. Peter calls, "Kevin! You spent $967 on room service?!" Kevin runs back to the hotel as the film ends.
I don't think so.
I made my family disappear.
This is my house. I have to defend it.
I'm kind of upset about it because I really like my family, even though sometimes I say I don't. Sometimes I even think I don't.
No offense, but aren't you a little old to be afraid?
So what else is new?
My family's in Florida, I'm in New York?
No offense, but that seems like sort of a dumb thing to do.
You can mess with a lot of things, but you can't mess with kids on Christmas.