The old Duke recounts a love story to a female patient in a contemporary care home from a notebook:
Noah Calhoun, a lumber mill worker, meets 17-year-old heiress Allison "Allie" Hamilton, spending the summer with her parents, at a funfair in Seabrook Island, South Carolina, in 1940. He pursues her, and they start dating.
Soon, Noah and Allie delivered an incredible and compelling portrayal of a boy and a girl driving down a long road without thinking about the repercussions. They fell in love with each other. They spent every waking hour together. They became inseparable very quickly.
One evening, Allie meets Noah's father, Frank Calhoun, and he likes her right away. But when Noah meets her parents, they don't like him. Noah takes Allie to the deserted Windsor Plantation that evening and promises to acquire and renovate it. They begin their first kiss while the sun is setting. Fin, a friend of Noah's, interrupts them and tells them that Allie's parents have called the police to seek her out.
When Allie and Noah return to her parents' house with Noah, Allie's mother, Anne, immediately makes it obvious they are against the connection and forbids her from seeing Noah. Anne mentions Noah as trash, which makes him upset. Allie follows Noah as he leaves, and when they dispute, She snaps at him and immediately regrets it.
They would leave right away for Charleston the following morning, Anne says. After failing to locate Noah to offer an apology, Allie asks Fin to tell Noah that she loves him. When Noah hears, he rushes to Allie's, only to find the gates locked.
Every day for a year, Noah writes to Allie, but Allie's mother stealthily intercepts the letters. He decides to quit writing after 365 letters go unanswered and move on. A state of war has existed between the United States and the Constitution of the United States against all enemies, foreign and domestic. He joins the army with Fin, who gets killed in the Battle of the Bulge. Allie works as a nurse in a military hospital when she meets Captain Lon Hammond Jr., a young lawyer from old Southern Money who is fabulously wealthy. To the joy of Allie's parents, they became engaged after a while.
After the war, Noah discovers that his father sold their house so that he could purchase The Windsor Plantation. When Noah went to Charleston to get the building plans approved, he saw Allie in a relationship with another guy. After seeing Allie that day, something inside Noah snapped. He convinces himself that if he fixes it, Allie will eventually return with him. Noah's father died in November.
After finishing the house, Noah refuses to sell it to anyone. While trying on her wedding gown, Allie collapses after she sees a newspaper photo of Noah in front of the newly refurbished home.
Allie asks Lon to go on a solo vacation before the wedding after her feelings for Noah resurface. She returns to Seabrook and finds Noah living in their dream house. The reader pauses the story here and goes on for his medical check. He suffers from heart disease and has had two small attacks in the last 18 months. The elderly guy responds that he is reading to Miss Hamilton to help her regain her memory when the doctor asks why he is doing so. He mentions that Miss Hamilton plays the piano from memory. At present, the senior woman is identified as Allie, who is now suffering from dementia. The true identity of Noah is Duke. Their Children and grandchildren arrive to see him and her, but Miss. Allie Hamilton doesn’t remember them or Mr.Noah Calhoun. When his children call him to come home with them, he is stubborn and refuses, saying, I’m not leaving her, and your mother is my home now. In the story, Noah takes Allie to a romantic place the next day. They reunite and finish their romance. Allie learns about the 365 letters from Noah, and they both realize that Allie never received them because of her mother's deliberate secrecy.
A few days later, Anne notifies Allie that Lon has arrived in Seabrook. She also admits that, like her daughter, she once had a love affair with a young guy from a lower class in Seabrook and still ponders how their lives would have been different if she had made another decision. She hands Allie Noah the letters and wishes her luck in her decision.
In their argument, Noah advises Allie to follow her desires rather than those of her parents or Lon. Crying and bewildered, she drives back to her hotel. Noah uses a pseudonym to avoid waking Allie up when she is confused. For him to be able to assist her in locating him again, she wrote the journal he read to her in the early stages of her illness. When he promised to read it to her practically every day, Noah almost kept his word.
When Allie asked Noah what happened at the end of the journal story in the notebook, he reminded her that she already knew. In the past, Allie told Lon she had been unfaithful. She follows her heart and returns to Noah, even though he still wants her back. He is briefly recognized and remembered by Allie. Duke responds that it might take up to five minutes when she wonders how long they have before she forgets again. She inquires about their children as they dance to their tune, "I'll Be Seeing You."
But as soon as Allie notices a stranger touching her, her dementia swiftly relapses, and she becomes terrified. She receives a tranquilizer to control her hysteria. Duke had a heart attack and is being treated in the nursing home, while Allie was taken to the dementia section.
Duke enters Allie's room in the middle of the night once he has recovered, despite being forbidden to do so. She recognizes him right away, and they kiss before falling asleep together. They both passed away quietly in their sleep, and the nurse discovered them the following morning still holding hands.
