I already forget how I used to feel about you.
When their relationship turns sour, a couple undergoes a medical procedure to have each other erased from their memories.
A man, Joel Barish, heartbroken that his girlfriend Clementine underwent a procedure to erase him from her memory, decides to do the same. However, as he watches his memories of her fade away, he realizes that he still loves her, and may be too late to correct his mistake.
A man awakes disheveled; impulsively, he skips work, heading instead to the shore. On this chilly February day, a woman in orange, hair dyed blue, chats him up: she's Clementine, he's Joel, shy and sad; by day's end, he likes her. The next night she takes him to the frozen Charles River. After, as he drops her off, she asks to sleep at his place, and she runs up to get her toothbrush. Strange things occur: their meeting was not entirely chance, they have a history neither remembers. Our seeing how the lacunae came to be and their discovery of the memory loss take the rest of the film.
Joel is stunned to discover that his girlfriend Clementine has had her memories of their tumultuous relationship erased. Out of desperation, he contracts the inventor of the process, Dr. Howard Mierzwaik, to have Clementine removed from his own memory. But as Joel's memories progressively disappear, he begins to rediscover their earlier passion. From deep within the recesses of his brain, Joel attempts to escape the procedure. As Dr. Mierzwiak and his crew chase him through the maze of his memories, it's clear that Joel just can't get her out of his head.
On a Valentine Day, Joel Barish feels the impulse of going to Montauk instead of working. After spending the cold day on the beach, he meets Clementine Kruczynski on the train station and they have a crush on each other. Joel and Clementine do not know that they were mates in the past. Joel has just erased Clementine from his memories when he found that Clementine did exactly the same, when their relationship ended. However, along his erasing process, Joel becomes astonished when he finds that he still loves Clementine and he does not want to lose her, fighting for keeping the memories of their moments together instead.
This is the story of a guy, Joel, who discovers that his long-time girlfriend, Clementine, has undergone a psychiatrist's experimental procedure in which all of her memory of Joel is removed, after the couple has tried for years to get their relationship working fluidly. Frustrated by the idea of still being in love with a woman who doesn't remember their time together, Joel agrees to undergo the procedure as well, to erase his memories of Clementine. The film, which takes place mostly within Joel's mind, follows his memories of Clementine backwards in time as each recent memory is replaced, and the procedure then goes on to the previous one, which is likewise seen, and then erased. Once the process starts, however, Joel realizes he doesn't really want to forget Clementine, so he starts smuggling her away into parts of his memory where she doesn't belong which alters other things about his memories as well...