In early 20th-century Montana, two brothers, Norman and Paul Maclean, grow up under the strict guidance of their father, a Presbyterian minister who instills in them a profound love for fly fishing as a metaphor for finding one's path in life. Norman, the older of the two, is reserved and studious, while Paul, the younger, is charismatic and rebellious. Their different temperaments set the stage for their divergent paths as they come of age, grappling with personal identity, family expectations, and the complexities of love and friendship against the backdrop of the beautiful Montana landscape.

As they move into adulthood, Norman heads off to college, aiming for a conventional career and life. Meanwhile, Paul stays in Montana, becoming a brilliant but troubled journalist known for his gambling and drinking. The brothers' rare reunions are marked by their shared love of fishing, which continues to be a central theme in their relationship, symbolizing both the bond and the divide between them. Their father's wisdom and the lessons learned through fly fishing in the stunning Montana rivers remain a guiding force, as each brother seeks to navigate his own current in the river of life, reflecting the broader themes of love, family, and the pursuit of individual destiny.