Macaulay Culkin stars as Kevin McCallister, who is once again separated from his family during one of their Christmas travels (following the first film). This time, the family is going to Miami, Florida for Christmas. Kevin makes it to O'Hare International Airport, but loses sight of his family while trying to get batteries for his Talkboy out of his father Peter's bag.
Seeing a man that is wearing the same coat as his father, he follows him toward a flight to LaGuardia Airport in New York City and doesn't realize where he is until the plane lands. While in New York, he decides to make the most of, as he puts it, "the greatest accident of my life". Along the way Kevin meets several people, including a lady (played by Brenda Fricker) who enjoys caring for pigeons, but creeps Kevin out at first.
In New York, Kevin decides he needs a place to stay. He decides to stay at the Plaza Hotel (after hearing about it on a TV game show the night before), placing Peter's credit card to check in. The concierge, Mr. Hector (played by Tim Curry), is suspicious of him the entire time he sees him there, going as far as sneaking into his room and prove Kevin a fraud. This attempt ends in failure as he is caught by Kevin using an inflatable clown to impersonate his Uncle Frank singing in the shower (which Kevin had recorded earlier on his Talkboy). The next morning Mr. Hector wants to apologize to Kevin's father for what he did the night before.
The next morning, Christmas Day, Mr. Duncan sends a whole truckload of presents to Kevin and his family at the Plaza Hotel as a reward for Kevin's role in the apprehension of Harry and Marv. His older brother Buzz suggests that had it not been for Kevin getting on the wrong plane, they would not be in the suite with the Christmas tree and gifts, and thinks it's only fair that Kevin get to open up the first present.
While everyone is opening their presents, Kevin notices that his turtledoves are on the room's Christmas tree and decides to head across the street to the park. He finds the pigeon lady feeding her pigeons and gives her one of the turtledoves, which serves as an affirmation of his promise from earlier. The pigeon lady is grateful for the gift and shares a hug with Kevin.
While all of this is going on Kevin's room service bill from his first stay at The Plaza, totaling $967.43, is delivered to the McCallisters' room. Buzz receives it and passes it along to Peter, who screams at Kevin from the hotel room regarding the charges. The film ends with Kevin running back to the hotel.