The story follows Dawson Cole James Marsden and his longtime love Amanda Michelle Monaghan as it shifts between their 1992 romance and their present, separate lives.
Dawson Cole works on an oil rig off the coast of Louisiana, where a catastrophic explosion hurls him into the sea and nearly takes him from the world. After months of healing, he learns that his close friend and surrogate father, Tuck, has died, and he returns home to fulfill Tuck’s final wishes with the lawyer he left behind. At Tuck’s house, he is surprised to discover that Tuck had also arranged for his high school girlfriend to join him, Amanda, who is now married.
In flashbacks, we learn that Dawson grew up in a troubled, violent family with an abusive father. As a teenager, he left that home and found shelter in the garage of Tuck Hostetler, a local mechanic who had recently lost his wife and came to regard Dawson as his own son. Dawson and Amanda met in high school, fell in love, and began a passionate relationship. On the prom afternoon, Dawson’s father and brothers beat Tuck, and Dawson, furious, goes to his father’s house with Tuck’s rifle intending to kill him. In the ensuing struggle, their cousin—an expectant teenage father—dies by accident. To secure a lighter sentence, Dawson testifies against his own father and brothers, which delays his parole for years and forces Amanda to choose college over waiting for him.
After Tuck’s death, Dawson and Amanda meet with the lawyer to scatter Tuck’s ashes at a cottage he shared with his wife. The two share a passionate night, and over lunch they discuss their future, during which she reminds him of the time she refused to visit him in prison. The next day, Amanda decides to return to her family and her strained marriage to fulfill her responsibilities, while Dawson stays behind at Tuck’s to restore the garden.
Amanda eventually splits from her husband and leaves a voicemail expressing her love, but before anything more can happen between them, Dawson is ambushed by his brothers and nearly killed as he’s about to be pushed onto a moving train. He manages to disable them and calls 911, only to be shot by his father as the authorities arrive.
Meanwhile, Amanda receives news that her son has been in a car accident and may need a heart transplant. That same night, as a donor is found, she dreams of Dawson sitting by her son’s bedside. When she is awakened by the doorbell, her mother delivers the crushing news that Dawson was shot and killed by his father.
One year later, Amanda’s son reveals that the donor’s name was Dawson Cole, a truth that shocks yet consoles her. She drives back to Tuck’s house, where she discovers Dawson’s letter left for her, expressing his deep love. Walking through the garden he lovingly arranged, she absorbs the memory and significance of their shared past, carrying it into the quiet, hopeful future that the garden represents.
