Summary
Highlights
Sadie and McKayla, obsessed with true crime and running a blog called 'Tragedy Girls,' lure and capture a notorious serial killer named Lowell. They reveal their intention to learn from him, but when Craig, a boy they used as bait, is found alive, Sadie brutally suffocates him. They dismember his body and dissolve it in acid to cover their tracks, then lock Lowell away.
The girls begin posting about Craig's disappearance, feigning concern and promoting their blog. They hatch a plan to commit murders and pin them on Lowell to gain more followers. Their first victim is McKayla's ex-boyfriend, Toby. They cause him to crash his motorcycle, and when he's still alive, they stab him multiple times, ignoring a passerby. Toby's death is initially ruled an accident, much to their dismay.
Angered by a rival and the cancellation of prom, Sadie and McKayla destroy Sylvia's scholarship project. Later, they ambush Sylvia at school, brutally decapitating her with a saw. To ensure it's not seen as an accident, they dismember her body. This gruesome act proves their serial killer theory, boosting 'Tragedy Girls' popularity and gaining them followers, interviews, and attention.
Jealous of local firefighter Big Al stealing their spotlight, the girls decide to poison him. Jordan, a classmate with a crush on Sadie, tries to investigate 'Tragedy Girls' on his father's computer. McKayla poisons Big Al's water, but Sadie, rushing because Jordan is coming, speeds up the process by attacking him. After a struggle, Sadie kills Big Al by dropping a barbell on his head. Lowell, the captured serial killer, manages to escape.
Jordan, suspicious of McKayla, steals her phone. Sadie plans to kill Jordan, but is swayed by his affections. Lowell, now free, confronts Sadie and Jordan. Lowell escapes, and Sadie, to conceal their secret, smashes McKayla's phone. At prom, Sadie is crowned queen. McKayla, arriving with Lowell, reveals their past—they murdered Jordan's mother as children. The girls kill Lowell after he attacks McKayla. Sadie then murders Jordan, and the duo sets the school on fire during prom, causing mass casualties and basking in the chaos. They become heroines, framing Lowell for all the deaths, and receive college scholarships, selling books, and planning a movie.