Donnie Darko (played by Jake Gyllenhaal) is a troubled teenager in suburban Virginia in October 1988. He appears to be suffering the symptoms of paranoid schizophrenia. At the start of the film, he has recently stopped taking his medication. His parents, Rose and Eddie (Mary McDonnell and Holmes Osborne) and his sisters, Elizabeth and Samantha (Maggie Gyllenhaal and Daveigh Chase), are concerned about him. One night at dinner, Donnie and his sister get into a profane argument during which Elizabeth reveals she knows Donnie is no longer taking his medication. Rose confronts Donnie in his bedroom asking him where her little boy has gone and who the stranger is who has taken his place. As she leaves the room, she hears him call her a "bitch" from the other side of the door. Feeling guilty, Donnie resumes taking his medication. On October 2, however, he sleepwalks and meets Frank (James Duval), a man in a menacing bunny costume. Frank tells him that in 28 days, 6 hours, 42 minutes and 12 seconds, the world will end. That night, a jet engine mysteriously crashes through the roof of the Darkos' house, destroying Donnie's bedroom.
As Eddie drives Donnie to the office of Dr. Thurman (Katharine Ross), Donnie's therapist, Eddie nearly runs over Roberta Sparrow, also known as "Grandma Death" (Patience Cleveland). A senile old woman who spends her days walking back and forth from her house to the mailbox across the street, Grandma Death whispers in Donnie's ear that all living things die alone. This greatly troubles Donnie, who worries that life has no meaning.
A few days later, Frank appears to Donnie in a hallucination and urges him to flood the private school he attends by breaking open the water main with an axe. Donnie also embeds the axe in the head of the school's solid bronze statue of its mascot and spray-paints "They made me do it" on the sidewalk. School is canceled that day and Donnie walks Gretchen (Jena Malone), the new girl in school, home. She reveals...