Joel Barish and Clementine Kruczynski, an unlikely couple, meet for the first time (or so it seems) on Valentine's Day. Joel, who is shy and neurotic, skips work and boards the Long Island railroad to Montauk, a place where Clementine is drawn to, but never explains why. As they are complete opposites, they initially have a great time together but eventually begin to wear on each other's nerves and have a fight. Clementine visits a futuristic service called Lacuna, a company that claims to erase unwanted memories, in order to move on. When Joel learns of this, he decides to do the same, but during the process, he discovers that the unprofessional "scientist" Patrick assigned to monitor the operation is Clementine's current lover. Furthermore, Mary, a free-spirited assistant, is not who she appears to be, and this remains a secret even to her for the time being.