Female doctor Kate (Sandra Bullock) moves out of her riverside hut in the suburbs because of her busy work. Before leaving, she left a letter in the mailbox, hoping that the next guest would help with the letter. Soon after, she arrives at the old site and finds a letter from the architect Alex (Keanu Reeves) in the mailbox, letter after letter. It turned out that they lived in two years apart. Although they were surprised, they were more willing to be each other's pen pals. They felt each other's existence again and again in different spaces. As the love grew, Alex decided to meet Kate, but they didn't know what kind of situation they would experience in this love that spanned time and space.