An FBI agent, struggling to overcome her own demons, is assigned to track down a brutal serial killer known for his methodical and grotesque killings. Dubbed "Longlegs" for his eerie and contorted movement, the killer leaves a trail of bodies across multiple states. As the agent delves deeper into the case, she uncovers a web of dark secrets connecting the killer to her own past, leading to a twisted confrontation that forces her to face the trauma she has long buried.