She can been seen in roles that include The Watermelon Woman, Chasing Amy, American Psycho and The L Word. Her latest screenplay, Charlie Says, tells the story of the women who killed for Charles Manson as they serve out the first few years of their prison term. Charlie Says is directed by Mary Harron and opened in theaters and on digital platforms in May of 2019. Guinevere has taught screenwriting at Sarah Lawrence College, Columbia University, University of Georgia, UCLA and NYU. She published an essay in The New Yorker in April of 2019, and will expand on that essay in book form in 2020.