At a modern-day nursing home, an elderly man, Duke, reads a romantic story from his notebook to a fellow patient.
In 1940, Seabrook Island, South Carolina, Noah Calhoun is smitten with 17 year old heiress Allison "Allie" Hamilton after seeing her at a carnival, and they have a summer love affair.
Duke is actually Noah, and was told by Allie during the onset of her illness to reread their journals to help her remember.
She briefly remembers who he is and they reconcile, but soon forgets and panics, forcing medical personnel to sedate her.
She then gives Allie the letters that Noah wrote to her, admitting that she hid them from Allie.
Allie confesses to Lon that she has been spending time with Noah, and tells him she knows she should be with him, but she remains indecisive.
When Noah gets the message he rushes to Allie's home, only to find the house empty.
Noah writes to Allie every day for a year but Anne intercepts the letters and they never reach Allie.
Noah has a heart attack and is sent to the hospital while Allie is sent to a dementia ward in the hospital.
He visits her room in the middle of the night, and she remembers him again, expressing that she may forget again.
Noah enlists with Fin to fight in World War II, where Fin is killed in battle.
Allie volunteers in a hospital for wounded soldiers, where she meets officer Lon Hammond Jr., a young lawyer who comes from old Southern money.
While visiting Charleston, Noah witnesses Allie and Lon kissing at a restaurant; he convinces himself that if he restores the house, Allie will come back to him.