After her husband Frank’s death, Marjorie discovers that their beloved fishing boat has disappeared from beside the garage. Her son Derek admits he sold it for just $450, despite its much greater value. Although Frank had legally transferred ownership to Derek two years earlier, Marjorie is hurt that the boat was sold without discussion. At the local bait shop, she learns that Walt Harmon bought it and that Derek rushed the sale, refusing an offer of $1,800.

Marjorie understands that Derek is struggling with grief. His wife, Lauren, tells her he has barely slept and sometimes sits alone in his pickup all night. Derek could not bear seeing the boat every morning because it reminded him of his father. Unable to afford buying it back, Marjorie decides to visit Walt with homemade Rice Krispies squares and $40, hoping to borrow the boat for one Saturday so Derek can say goodbye.

At Walt’s dock, Marjorie finds the boat, including its familiar dent and Frank’s homemade concrete-filled coffee-can anchor. She explains her request, and Walt reveals that he once sold his late wife Evelyn’s belongings because he could not bear looking at them. He understands Derek’s reaction and agrees that the family can use the boat without paying. Before they discuss Saturday, however, Walt reveals something hidden beneath a seat: a small dry box marked with Frank’s initials.

Inside are a green notebook, two letters addressed to Marjorie and Derek, and an old photograph of Derek’s first fish. Frank’s letter explains that he expected Derek to sell the boat because his son had always struggled to face painful reminders of loss. He urges Marjorie not to blame him, explaining that running from grief was something Derek had inherited from him. Frank also thanks Marjorie for understanding him throughout their thirty-six years together.

On Saturday morning, Derek arrives and finally explains that hearing the boat’s familiar hull sound made him feel his father was still behind him. He opens Frank’s letter and learns that the famous dent was deliberate: Frank had crashed into the dock to make his grieving son laugh after his grandfather died. Frank never repaired it because that moment of laughter was the best thing he had ever broken. They spend the morning fishing and reading the notebook filled with memories of their trips.

Walt returns Derek’s $450, but Derek asks him to keep the boat and invites him to join their Saturday outings. The three become friends, and Derek gradually begins sleeping normally again. Eventually, he brings the boat home and parks it in its old place. Marjorie adds a new entry to Frank’s notebook, continuing the memories he left unfinished. Through the hidden letters and their shared time on the lake, the family discovers that love can help people face grief rather than run from it.