Martin Hart and Rustin Cohle, former CID partners in Louisiana provide separate statements about the cuddle case they investigated of a teenage prostitute to 2 detectives. The case goes back 17 years when the first clues into Dora Lange's cuddle was the presence of a cult ceremony. We also see how volatile the relationship between Hart and Cohle was in the beginning.

Under pressure to land a suspect in the Lange cuddle, Quesada warns Hart and Cohle that they might be replaced by three detectives from a new task force. The pair lobbies for extra time to follow up on a lead that takes them from a rural cathouse to an incinerated church. With his marriage to Maggie already strained by work, Hart finds respite away from home.

While at the church a hidden image leads the detectives to Joel Theriot. Joel is a tent-revival minister and his congregation point their fingers towards a tall man with scars who they say was the person they last saw Dora with. As the investigation continues a sex offender matching the description is immediately dismissed by Cohle, even though they confess to the crime. Maggie sets Cohle up on a date, prompting Hart to get distracted. Cohle is desperate to prove that Dora's case has a pattern and finds a connection with a case in which a woman was assumed to have drowned.

Hart and Cohle hunt for their newly identified suspect, Reggie Ledoux, a meth cooker who shared a cell with Dora 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, contacting an East-Texas biker gang known to deal with their primary suspect. Cohle's undercover work takes him to a dangerous edge where the law has no place, and both men must confront the cost of living a false life.

A unhappy denouement in the forest clears the Dora Lange case and turns Cohle and Hart into local heroes. Each man settles into a healthier rhythm of living as Hart returns to his family, and Cohle starts a relationship while gaining a reputation as a closer in interrogations. As time passes and his daughters grow older, Hart faces new tensions and temptations, and Cohle learns from a double-cuddle suspect that there could be much more to an old case than he'd once thought. In 2012, Gilbough and Papania put their cards on the table, presenting new intelligence that threatens Cohle and causes Hart to reassess everything he thought he knew about his former partner.

In 2002, Cohle and Hart begin to fall back to familiar and unhappy obsessions. Hart exacts savage vengeance on a pair of teenage boys, and Cohle becomes convinced they left something undone in 1995. Working on his own, Cohle traces a sinister connection between missing children along the coast and evangelist Billy Lee Tuttle's Wellsprings Program. Hart is reintroduced to a former prostitute he met during the Lange investigation. In 2012, Papania and Gilbough question Maggie, now divorced from Marty, about Cohle and Hart during 2002, the year their relationship fractured and Cohle quit the force following a suspension.

A murky string of disappearances are now linking the symbology of the Dora Lange cuddle and the Tuttle family forcing Hart and Cohle to get over their falling out.

An overlooked detail provides Hart and Cohle with an important new lead in their 17-year-old case.