In the quaint Midwestern town of Rosedale, high school seniors McKayla Hooper and Sadie Cunningham find themselves deeply fascinated by the dark allure of murder and fame. They run a true crime blog named Tragedy Girls, which quickly spirals into an obsession as they become determined to achieve notoriety by any means necessary. To escalate their quest for attention, they manipulate their friend Craig Thompson as bait to attract the infamous serial killer Lowell Orson Lehmann. However, their efforts are thwarted when Lehmann dismisses their advances. Undeterred, the duo resorts to nefarious tactics, capturing Lehmann and fabricating a series of murders, shifting the blame onto him.
The disappearance of Craig sends ripples of worry throughout the community, prompting McKayla, Sadie, and their friend Jordan Welch to feign a narrative of a serial killer terrorizing the town. Yet, their plot only serves to spook Jordan’s father, Sheriff Blane Welch, who remains skeptical of their claims. Tensions rise as McKayla’s ex-boyfriend, Toby, garners more online followers than the two girls, igniting her rage. In a moment of reckless ambition, McKayla and Sadie eliminate Toby, masquerading his death as an unfortunate accident that incites community indignation. Their next target is the cheerleading captain, Syl, whose demise they meticulously stage as a homicide.
At Syl’s memorial, local firefighter Big Al pledges to uncover the truth behind the murders, blissfully unaware of the deadly games at play. Meanwhile, Lehmann attempts to create discord between McKayla and Sadie, instigating fear that Sadie plans to double-cross her. As the tension escalates, their plan turns murderous; they set their sights on Big Al, attacking him while he works out at the gym. In a brutal clash, he fights back, but ultimately falls, leaving behind a shocking reminder of their actions.
Amid the chaos, a town meeting called by Mayor Campbell ignites a media frenzy, where McKayla and Sadie manipulate the public to turn against local law enforcement, displaying the gruesome image of Big Al’s severed head to ignite fear and mistrust. Their bold display culminates in a rally pushing against authority, but their efforts fall short when Lehmann escapes and retaliates against the mayor, dismantling his authority.
A rift forms as Jordan aligns himself with law enforcement, rejecting the girls’ dubious tactics. The fallout from this decision sees McKayla and Sadie confront Jordan, only to discover he’s been secretly investigating them. This treachery leads to a dramatic showdown, with Lehmann violently interrupting, leaving Jordan's life hanging by a thread.
As desperation mounts, McKayla breaks into Sheriff Welch's home, rousing him to save Jordan from a fatal encounter. Meanwhile, Sadie seizes the moment to obliterate evidence of their crimes, jeopardizing their already fragile relationship. Weeks later, Sadie basks in the admiration of Sheriff Welch at a public event but pointedly excludes McKayla from her speech, leading to a devastating split.
On prom night, the tension reaches its peak as Sadie dates Jordan while McKayla finds herself allied with Lehmann. Chaos unfolds as they take the life of their teacher, and McKayla reveals the chilling truth about their childhood murders of Jordan's mother. Unbeknownst to Sadie, Jordan overhears and attempts to escape with her, but they're trapped by both McKayla and Lehmann in a tense confrontation.
In a shocking twist, Lehmann turns against Sadie, but McKayla intervenes and fatally shoots him, prompting an unsettling reconciliation between the girls. In their final act of defiance, they brutally hang Jordan before igniting the gymnasium, resulting in the tragic deaths of 124 innocent prom-goers.
In the aftermath, the town grapples with the horror left in their wake, while Sheriff Welch resigns, consumed by grief. McKayla and Sadie, however, appear untouched by their past atrocities, moving forward as if nothing ever happened, ready to embrace a future steeped in darkness yet again.
