Sarah's a struggling actress. She works at a Hooters-esque restaurant. Sarah performs oral sex on the Executive Producer of an Astraeus Pictures film in order to get a "part that will make her a star." Following that, she gets infected with something horrible that makes her vomit non-stop, lose her hair, have her period, and have something crawling around under the skin of her stomach.
Voices tell her to embrace her true self and she then kills all her friends (except for her roommate), buries herself in the dirt as some rich-looking people chanting "Hail Astraeus" form a star on top of her in lights. She emerges with claw-like nails, emerald green eyes, and a bald head. On top of the spot where she was buried, there is a box on top of where she was buried that says, "Happy birthday," on the card.
She goes back to her apartment -- her roommate apologizes for telling their friends that Sarah had sex with the Executive Producer for a part. The roommate goes into Sarah's room and finds her (naked, bald, with emerald eyes and claw fingernails) under the sheets with candles lit all over the room; Sarah tells her to say goodbye and then kills the roommate by kissing her (and then blood starts coming out of the roommate's mouth.)
Following that, she opens the box and inside is a dress, a wig, and a necklace with a star - the symbol of the studio - on it. She puts them on, looks fantastic, and the movie ends.