The film begins with old photographs of the Maclean family as Norman narrates over the images. We see a train arriving into Montana, and it is carrying Norman home after he has been away for six years studying at Dartmouth. He is welcomed home by his father and mother, but his brother Paul is unable to be there to greet him. The next day Norman goes to see Paul at the newspaper office where he is a reporter. Paul offers him a swig of liquor to celebrate his return to which Norman drinks because his little brother says that him being out east has made him soft. They go fishing in the Blackfoot River, where Norman has lost a bit of his touch as a fly fisherman, but he sees his brother has become an artist at the sport while he was away at school
Soon after, Norman meet Jessie, a young woman from Montana at a fourth of July dance who he takes a liking to and she to him. We learn that Paul is in serious debt to bad men through a poker game he plays at an out of the way bar. The men who run the bar have set it up in order to cover the fact that they are in business for gambling and prostitution. Paul is then arrested for getting into a fight with a guy who is racist and insults his girlfriend who is Native American. Norman has to bail his little brother out in the middle of the night and he learns that his brother is in bad shape, but is willing to cover for him.
Norman and Jessie begin to spend more time together and she asks if he will take her brother Neal fishing with them as he's home from California visiting. Norman agrees and he and Paul invite him along, but when Neal arrives the next day he's drunk and with a woman he met the previous night at a bar. They decide not to interfere and eventually Neal is left without his clothes passed out in the sun where Norman and Paul leave him for the entire time they are fishing. This leaves him burnt to a crisp which upsets Jessie when she sees her brother, but Norman doesn't tell her what actually happened to save face for Neal. She asks Norman to leave, but ironically she has to drive him home because he doesn't have a car. She then drives down the railroad tracks to avoid a water ditch, taking Norman through a train tunnel and over a very high bridge which terrifies Norman.
She eventually drops him home and he attempts to tell her that he's falling in love with her. Paul arrives to apologize about what happened to Neal and attempt to take the blame for it. All hope is not lost with Jessie as she invites Norman to the train station to see her brother off. It is here where Norman reveals to her that he has been offered a job at the University of Chicago working in the English Literature Department. Norman is ready to marry Jessie and tells Paul while they are fishing. Paul turns his back to his brother though he's happy for him, and Norman invites him to come with them, but Paul says he's never leaving Montana.
Norman, Paul and their father decide to go on one last fishing trip before Norman leaves for Chicago. They spend the entire day with each other and it is capped off with Paul making one of the greatest catches any of them have ever seen. Their father calls it perfection, and Paul emerges from the river with a fish a third of the length of his body. His father snaps a photograph for their mother. This will be the final time they all fish together, as Norman is later called by the police who tell him that Paul has been beaten to death in an alley.
After returning to Montana years later, Norman is asked by his father is he knows everything about Paul and what happened to him. Norman keeps the whole truth from him, and Reverend Maclean gives his final sermon on loving someone fully even though we don't know everything about them. We then see Norman as an old man fly fishing in the river. Everyone he's loved has since passed away and his final words of the film are, "I am haunted by waters."
