Marty and Rust zero in on their killer on the season finale of True Detective. The episode begins with the same man we saw in the final scene of the penultimate episode. The man with the scars on his face, Errol Childress, is talking to a body tied down to a bed frame of some sort. As he leaves he addresses the figure as "Daddy." Inside his dilapidated house, is a collection of dolls and a simple minded woman who he seems to have a sexual relationship with.
Back on the boat, Rust makes Sheriff Steve watch the tape. Steve's reaction is similar to Marty's when he also saw the tape. Steve says he didn't mark the initial report on the Fontenot girl as made in error, it was his boss, Sheriff Childress. Rust believes him but he and Marty still decide to take his gun and badge. As added insurance against Steve taking action against them, Rust has his friend from the bar fire some sniper rounds into Steve's car as a warning.
As Marty and Rust dig back into old case files again, Rust says something that helps Marty make a crack in the case. I minor detail leads them to a retirement home, where a woman helps them to identify the man with the scars's whereabouts.
Marty and Rust are nearly killed by Errol, but Rust kills him in the end. They are rescued by the police and recover in the same hospital.
Rust shares his near death experience with Marty before asking him to get him out of the hospital.