In a small southern Illinois town, Emily Ahrens, a rather plain, unexceptional 17-year-old girl, dies suddenly, horribly and inexplicably, at home. There appears to be no rational explanation for her death. Tests soon confirm that Emily died of kidney failure due to arsenic poisoning. Tests also confirm that she was not pregnant. A coroner's inquest, called to decide whether her death was suicide, accident, homicide, natural or undetermined concludes the death is undetermined. With no evidence of foul play, local authorities are reluctant to investigate. The girl's father, Walt Ahrens, a local car dealer, refuses to let the matter drop and begins obsessively seeking answers, even as his family begs him not to, even as the townspeople seek to put the tragedy behind them. Stonewalled, Walt hires a shady private investigator from the city to look into the circumstances of his daughter's death, but he too fails to turn up any answers, only more questions, before dumping the case back into Walt's lap. When the desperate father turns up the screws on one rather unsavory suspect, a fatal accident ensues, and circumstances begin to spiral out of control.