While serving in the United States Army Special Forces in 2007, John Tyree (Channing Tatum), a Staff Sergeant, is lying on the ground after being shot multiple times in the neck and body, with his comrades gathered around him. In a voiceover, he recalls a childhood trip to the U.S. Mint and compares himself to a coin in the United States Military before stating that the last thing he thought of before he blacked out was “you”.
In 2001, John is on vacation in Charleston, South Carolina while on leave. He meets Savannah Curtis (Amanda Seyfried), a college student on spring break, when he fetches her purse from the ocean after it gets knocked over the pier. She invites him to a bonfire party that same night where he meets her neighbor, Tim Wheddon (Henry Thomas), and his son Alan (Luke Benward), who has autism. Over the course of two weeks, they go on several dates and fall in love. Savannah also meets John’s father (Richard Jenkins), a reclusive man who is obsessed with his coin collection, a fixation that intrigues her but irritates John and causes distance between them.
One afternoon while taking a walk on the beach, Savannah mentions to John that his father, like Alan, may have high-functioning autism. This instantly upsets John who refuses to admit that his father has autism, and storms off. In the parking lot, Savannah’s friend Randy (Scott Porter), who also has a crush on her, makes a comment that provokes John to start a fight and, in the process, he accidentally punches Tim. Savannah sees the commotion and stops speaking to him. The following day, John visits Tim to apologise and he offers to give Savannah a message, which he scrawls down on the back of Tim’s water bill. Knowing he has to go back soon, she drives to his house and they spend one last day together, parting with, “I’ll see you soon then” rather than a goodbye.
John and Savannah continue their relationship through letters. Meanwhile, back home, Savannah spends more and more time with Tim and decides she wants to work with children with autism, and plans to build a farm and stables for horses where they can enjoy the outdoors and animals of the same nature. Over the twelve months they’re apart, they expect to build a life together when John leaves the army, but in 2001 when the September 11 attacks occur, he reconsiders and ultimately chooses to re-enlist, causing an argument between them. Over the next two years, the romance goes on through their letters. After a time, John finds himself anxiously awaiting the next letter, but when it arrives it is a Dear John letter, informing him that she has become engaged to someone else. Upset, John burns all of Savannah’s letters.
Despite being wounded and encouraged to return home, John re-enlists. After four more years and many missions, while waiting to receive orders on his unit’s next deployment, John is informed that his father had a stroke. When John arrives at the hospital he learns that his father is still alive but in grave condition. John writes a letter to his father, which he reads to him at the hospital; John’s voiceover at the beginning of the film was from this letter, in which he told his father that the first thing to cross his mind after he was shot was coins, and the last thing to cross his mind before he lost consciousness was his dad, ultimately the most precious person in his life. Soon afterwards, his father dies.
John goes to visit Savannah and learns that she has married Tim and had to abandon her dream of a riding camp for kids with autism because of Tim’s fight against lymphoma. John goes with her to visit Tim in the hospital. Tim tells John that Savannah still loves John and she has never forgotten him. That night, Savannah asks John to stay for dinner. At the table, John asks Savannah why she did not even call him and she says it was because just hearing his voice would make her change her mind. As John goes towards the door, Savannah says “I’ll see you soon then”. She asks him to reply the same but he replies “Goodbye, Savannah” and leaves.
John decides to sell all of his father’s coin collection except the mule that John found, to raise money, which could help Tim in his treatment. Back in the army, John uses the mule as a charm. He receives a letter from Savannah telling him that Tim died after two months and ending with “I’ll see you soon, then.” Later, John—now a civilian again—coincidentally sees Savannah at a coffee shop and they hug.