Two former Louisiana State CID partners give statements to investigators about a murder 17 years previous. As they look back, details of the crime, replete with occult overtones, are accompanied by insights into the detective's volatile partnership and personal lives.

Under pressure to land a suspect in the Dora Lange murder, and under threat of being replaced by a new occult-crimes task force, Hart and Cohle lobby for extra time in order to follow up on a lead that takes them from a rural cathouse to an incinerated church.

A hidden image at the burned-out church leads Cohle and Hart to a minister whose parishioners finger a scarred, tall man seen with Dora Lange. Looking to establish a pattern of murder, Cohle pores over old cases, finding a link with a woman who drowned years earlier.

Hart and Cohle hunt for their newly identified suspect, Reggie Ledoux, a meth cook who shared a cell with Lange's husband and recently skipped parole. As Hart's personal life collapses around him, Cohle immerses himself in an old criminal identity from his narco days.

Violent denouement in the forest clears the Dora Lange case and turns Cohle and Hart into local heroes. As time passes, Hart faces new tensions and temptations, and Cohle learns from a double-murder suspect that there could be more to an old case than he'd once thought.

In 2002 Cohle and Hart begin to fall back to familiar and violent obsessions. Hart exacts savage vengeance on a pair of teenage boys, and Cohle becomes convinced they left something undone in 1995. 2012, and Maggie sheds light on when Cohle quit the force.

Hart and Cohle forge a truce and probe a murky conspiracy of disappearances connected to the Dora Lange murder, a path of connections that leads to the Tuttle family. The pair then uncover a connection to an old colleague and enact a plan to draw him out.

After their interrogation of Geraci yields new info but no critical breaks, Hart and Cohle find themselves back at square one. However, a photograph, along with a homeowner's old tax records, provides the pair with a vital new lead in their 17-year-old case.