Alton Richards is a soon-to-be high school senior whose summer is not going well. His girlfriend broke up with him only to start dating his best friend, Cliff. The Richards family struggles financially, unable to complete the swimming pool started in their backyard; Alton’s car has mechanical issues; and his dad gets laid off. Summer stretches before him, but he is too lazy to search for a job.
Lester Trapp, Alton’s gruff great uncle, is a rich, aging diabetic and accomplished bridge player — almost a Grand Life Master. Alton’s family loves Uncle Lester for his money, which they morbidly have hoped and planned to inherit for much of their lives. They believe they compete with the Castaneda family for the inheritance. The Castaneda family stems from those related to Uncle Lester’s former bridge partner.
When diabetic complications result in Uncle Lester’s blindness, he hires Alton for four days a week to drive him to his bridge club and be a cardturner in his bridge games. Though initially reluctant, Alton is intrigued by the game, and he begins to appreciate and eventually enjoy bridge. Alton calls his uncle Trapp because that’s what everyone in the bridge club calls him.
One day a girl from the Castaneda family appears at the club to play as Trapp’s partner. At 17, Toni is Trapp’s protégé and his former cardturner. Alton’s mother has told him for years that all of the Castanedas are crazy, so he scrutinizes Toni for signs of her schizophrenia. Toni is already an amazing bridge player for her age, but it is, in part, because she hears a voice telling her which cards to play. The voice belongs to her grandmother, Annabel, who died 40 years ago and who was Trapp’s perfect bridge partner.
When Toni phones Alton (because Annabel’s voice tells her to), she offers to teach him what she knows about bridge. They begin to play on their own, apart from Uncle Lester, and Alton experiences a growing attraction to Toni.
Alton travels with Trapp to a regional tournament. During the tournament, Trapp’s memory begins to fail, and he leaves in the middle of a round; Alton has to substitute. Trapp and his entourage return home. Trapp hopes to rest and recover enough to play in the upcoming national tournament. Yet five days later, he dies, and he leaves almost everything to charity.
To honor Trapp’s memory, Toni and Alton decide to play bridge at the club. Toni has heard Annabel’s voice since she was 6, and now Alton discovers that he can hear — or perceive — Trapp advising him which cards to play. Together they play not only as themselves, but also as Annabel and Lester — and they win first place. Alton begins to perceive Trapp’s voice outside of bridge club, too. Driving Toni home, he hears Trapp give directions that lead to Trapp’s house. Eventually, the teens gain access to the house, based on clues Trapp provides. As they search the house, they come to the realization that Trapp and Annabel want to play bridge at the national tournament by “channeling” Alton and Toni.
Alton and Toni arrive in Chicago for the National Pairs Tournament, sign in and play as Lester Trapp and Annabel Finnick (her maiden name). They win the championship and leave just as Lester and Annabel’s names are called to receive the trophy.