In a nursing home, resident Duke (James Garner) reads a romance story to an old woman (Gena Rowlands) who has senile dementia with memory loss. In the late 1930s, wealthy 17-year-old Allie Hamilton (Rachel McAdams) is spending summer vacation in Seabrook. Local worker Noah Calhoun (Ryan Gosling) meets Allie at a carnival and they soon fall in love with each other. One day, Noah brings Allie to an ancient house that he dreams of buying and restoring and they attempt to make love but get interrupted by their friend. Allie's parents do not approve of their romance since Noah belongs to another social class, and they move to New York with her. Noah writes 365 letters (one a day for a year) to Allie, but her mother Anne Hamilton (Joan Allen) does not deliver them to her daughter. Three years later, the United States joins the World War II and Noah and his best friend Fin (Kevin Connolly) enlist in the army, and Allie works as an army nurse. She meets injured soldier Lon Hammond (James Marsden) in the hospital. After the war, they meet each other again going on dates and then, Lon, who is wealthy and handsome, proposes. Meanwhile, Noah buys and restores the old house and many people want to buy it. When Allie accidentally sees the photo of Noah and his house in a newspaper, she feels divided between her first love and her commitment with Lon. Meanwhile, Duke stops reading to the old lady since his children are visiting him in the nursing home.