Charlie Simms is a student at an exclusive New England prep school, Baird. Unlike most of his peers, Charlie was not born to a wealthy family and attends Baird on scholarship. To pay for a flight home to Oregon for Christmas, Charlie accepts a temporary job over Thanksgiving weekend looking after retired Army Ranger Lieutenant Colonel Frank Slade, who Charlie discovers to be a cantankerous blind alcoholic. Charlie's first conversation with Slade doesn't go well: Slade berates Charlie for talking too much about his personal life and loudly orders Charlie out of the guest house he lives in on his niece's property. When Charlie talks to Slade's niece, saying that he thinks he blew it with her uncle, she tells him he has to take the job since he's the only person who applied.
Charlie and George Willis, Jr., another student at the preparatory school, witness several students setting up a prank for the school's headmaster Mr. Trask. Following the prank, Trask presses Charlie and George to divulge the names of the perpetrators. Trask offers a bribe, a letter of recommendation that would virtually guarantee his acceptance to Harvard. Charlie continues to remain silent but appears conflicted.
Shortly after Charlie arrives, Slade, without the knowledge of his niece, unexpectedly whisks Charlie off on a trip to New York City. Slade has reserved a room at the Waldorf-Astoria and during dinner the upscale Oak Club, Slade glibly states the goals of the trip, which involve enjoying luxurious accommodations in New York before committing suicide. Charlie is taken aback and does not know if Slade is serious. The next morning, Charlie awakes to find Slade in his bedroom expertly assembling his Colt service pistol. Charlie is somewhat alarmed and asks Slade to give up the pistol; Slade refuses. Charlie asks him for the bullets and Slade complies.
They pay an uninvited visit to Slade's brother's home for Thanksgiving dinner. Slade is an unpleasant surprise for the family, as he deliberately provokes everyone and the night ends in acrimony. During this time the reason behind Slade's blindness is also revealed: one of Slade's relatives, Randy, tells the story about how Slade used to juggle grenades while drunk. One grenade got away from him and exploded, causing his blindness. When Randy calls Charlie "Chuckie", Slade suddenly explodes, grabbing him by the neck, threatening to kill him if he doesn't apologize to Charlie. Slade and Charlie leave, Slade saying goodbye to his brother and telling him he's never been a good person.
As they return to New York, Charlie tells Slade about his complications at school. Slade advises Charlie to inform on his classmates and go to Harvard, warning him that George will probably be pressured into revealing the identities of his friends, however, with his influential father (also an alum of Baird) behind him, his punishment will likely be light. Later at a restaurant, Slade is aware of Donna; a young woman waiting for her date. Although blind, Slade leads Donna in a spectacular tango ("Por una Cabeza") on the dance floor.
That night, he hires a female escort recommended to him by their driver, Manny. While Slade enjoys his evening with the escort, Charlie calls the ski resort that George and Harry (the student who planned the prank on Trask) are spending the break at and finds out from George that Trask has elevated his investigation of the prank and that George's father has become involved. The phone call makes Charlie more tense than ever.
Deeply despondent the next morning, Slade responds to Charlie's suggestion that they test drive a Ferrari. Charlie lets Slade drive the car and Slade begins speeding, attracting the attention of a police officer (Ron Eldard), whom Slade manages to appease without giving away his blindness. The leave the Ferrari dealership, Slade more depressed than ever. While they walk back to the Waldorf, Slade deliberately marches out into traffic and collapses on the street. Charlie is able to pick him up and they continue.
When they return to the hotel, Slade sends Charlie out on a list of errands. Charlie initially leaves the room but quickly becomes suspicious. Charlie returns to find Slade in his military uniform, preparing to commit suicide with his pistol. Charlie intervenes and attempts to grab Slade's gun. Slade, however, easily overpowers him, threatening to shoot Charlie before himself. They enter a tense argument, however, after Charlie bravely calms Slade, he backs down. Slade agrees to take Charlie back to Baird, Charlie having missed his flight.
Manny drives the two back to Baird. Slade gives Charlie the money he owes him in cash and then touches Charlie's face, feeling for the first time how Charlie looks. He also offers Charlie any references he many need in the future and has Manny drive him home.
At school, Charlie and George are subjected to a formal inquiry in front of the student body and the student/faculty disciplinary committee. As headmaster Trask finishes his interrogation of George and turns his attention to Charlie, Slade unexpectedly returns to the school, joining Charlie on the auditorium stage for support. George has already divulged the names of the perpetrators, qualifying that his vision wasn't clear. When pressed for more details, George passes the burden to Charlie. Although struggling with his decision, Charlie gives no information, so Trask recommends Charlie's expulsion.
At this, Slade cannot contain his silence any longer and launches into a passionate speech defending Charlie and questioning the integrity of a system that rewards informing on classmates. He tells them that Charlie has shown integrity in his actions and for the committee to not expel him because this is what great leaders are made of and he will make them proud in the future. The disciplinary committee decides to place on probation the students named by George, and to give George neither recognition nor commendation for his testimony. They excuse Charlie from any punishment and allow him to have no further say in the inquiries, to loud applause from the student body.
As Charlie escorts Slade to his limo, a female political science teacher, Christine Downes, who was part of the disciplinary committee approaches Slade, commending him for his speech. Seeing a spark between them, Charlie tells Ms. Downes that Slade served on President Lyndon Johnson's staff. A romantic prospect is hinted between Slade and Ms. Downes as they part ways.
Charlie takes Slade home, where they go their separate ways. The colonel walks towards his house and greets his niece's young children happily as Charlie watches by the limo.