- Directors: Michel Gondry
- Producers: Anthony Bregman
- Writers: Michel Gondry, Charlie Kaufman, Pierre Bismuth
- Genres: Drama, Romance
- Actors: Jim Carrey, Kate Winslet, Kirsten Dunst, Mark Ruffalo, Elijah Wood, Tom Wilkinson, Jane Adams, David Cross, Thomas Jay Ryan
Emotionally withdrawn Joel Barish (Jim Carrey) and dysfunctional free spirit Clementine Kruczynski (Kate Winslet) meet each other for the first time at a beach party in Montauk, New York, and subsequently become romantically involved. However, two years into their relationship, they fall out of love with each other. Clementine discovers the services of Lacuna, Inc., a firm led by Dr. Mierzwiak (Tom Wilkinson) that claims to be able to erase all specific memories from a person’s mind. Clementine opts to have Lacuna erase Joel from her mind, handing over all of her possessions relating to their romance. When Joel seeks out Clementine the next day to try to make up, he finds she is completely unaware of who he is and is being wooed by Patrick (Elijah Wood), a technician from Lacuna who became smitten with Clementine and is using her past memories and the items given to Clementine by Joel to seek her affection. Joel investigates further and discovers Lacuna, opting to have his mind wiped of Clementine, giving them all the items he believes came about from his relationship with her.
The Lacuna technicians, Patrick and Stan (Mark Ruffalo), arrive at Joel’s apartment to perform the mind wipe as he sleeps, an all-night process; Mary (Kirsten Dunst), Stan’s girlfriend who is also a Lacuna employee, shows up later. Patrick leaves the apartment to spend time with Clementine. Stan and Mary are left to mind the machine but instead have sex and get stoned. Inside Joel’s mind during a lucid dream, Joel discovers his memories of Clementine are being erased in reverse order, and as he experiences the earlier, happier times with her, he becomes aware that he wants to stop the procedure and keep the memories, and begins to fight the mind wipe by trying to hide Clementine in deep memories of his mind. Joel’s resistance causes the machine to fault, and Stan and Mary are forced to call Dr. Mierzwiak to help finalize the procedure. While Dr. Mierzwiak is able to restore the process to normal, his arrival brings about several awkward feelings between himself and the stoned Mary. Shortly later she learns that she had her mind wiped of her former affair with Dr. Mierzwiak. Joel finds he cannot stop the process, but before his last memory of Clementine at the Montauk beach house is erased, she tells him she loves him and to “meet me in Montauk.”
Joel wakes up the next day and decides to skip work, instead taking the Long Island Rail Road train to Montauk where he happens to meet Clementine. Neither aware of who the other is, they quickly bond and begin to form a new relationship. The same day, Mary quits her job and steals the client files from Lacuna and mails them back to their clients. After returning to the city, Joel drives Clementine to her home to get her toothbrush so she can spend the night at his place, but is met by Patrick, who is there to continue to woo Clementine and wonders why Joel is still seeing her. When Clementine returns, she finds her Lacuna file in the mail and plays the tape from it for her and Joel, causing Joel to think that she is toying with his feelings, after which he forces her to leave his car and drives off alone. Patrick attempts to cheer Clementine up but she verbally lashes out at him and breaks off their budding relationship. Clementine travels to Joel’s apartment to find Joel with his own Lacuna tape and holding a drawing from their former relationship that he missed when handing over his possessions. They both become aware of the truth of their former relationship. The two recognize that their relationship may have problems based on their past, but decide not to let those failings prevent them from seeing other, and the movie ends with them in a teasing snowball fight on the Montauk beach.