On Mulholland Drive in Hollywood, a woman named Rita (Laura Haring) is in a car accident. Two other men in the crash who apparently didn't look very serious were killed on the spot, and Rita was lucky to escape. But she was completely amnesiac, unable to even remember her own name. She got out of the car and stumbled to an apartment, hiding in the bushes outside the apartment.
Meanwhile, Betty (Naomi Watts), a blonde girl who aspires to be an actress, arrives in Los Angeles with a dream, and an old couple on the same plane with her has an odd smile, and she borrows to live in Aunt Ruth's apartment. Betty is surprised to find a strange amnesiac woman in the room, who calls herself Rita, a dark-haired woman with a large amount of cash and a mysterious blue key in her purse.
Betty decides to help Rita retrieve her memories, while they discover that a killer is looking for Rita. At Danny's, Rita remembers Muheland Road and, after looking at the waiter's badge, comes up with a name called "Diana." Betty and Rita find Diana's apartment in the Muheland Road neighborhood, they enter through the window and are surprised to find a rotting female corpse on the bed of the apartment, the panicked Rita is very frightened, Betty is seduced by Rita's weakness, beauty and mystery, they have same-sex love, and then the sleeping Rita shouts a word in her dream: Cerensi. As if remembering something, Rita takes Betty to a club called "Ceyrensi" at two o'clock in the morning, where the stage magician and the female singer shudder with a bizarre performance that ends when they find a mysterious blue box. Back at home, Rita finds the blue key and opens the blue box, at which point Betty suddenly disappears, leaving only the dark blue box in the room...