A mysterious stalker puts a viral video on YouTube which Emily (Emma Stone) becames embarrassed after her mother (Andrea Martin)'s death.
- Emma Stone as Emily Crosby, the main character in the film and a student on Winsdor College
- Britt Robertson as Lizzy Cameron, she is Emily's friend and one of the murders of Ohio Killing Spree
- Emma Roberts as Kimberly Crosby, Emily's twin sister and the main killer
- Brooke Shields as Melissa Cameron (in the ending, she is now Adams), a reporter and Lizzy's older sister and the main tritagonist
- Matthew Broderick as Deputy Sheriff Steve Adams, the film's main deuteragonist