'The Leftovers' season-finale director breaks down the hardest scene to shoot

Warning: Spoilers if you haven't seen the season finale.

Sunday's episode of "The Leftovers" marked the end of the highly satisfying second season. Along with wrapping up a lot of important story arcs, it saw one of the most memorable scenes so far when Kevin (Justin Theroux) is shot and brought back to that hotel purgatory he was in during episode eight.

In the finale, John (Kevin Carroll) finds out that Kevin's palm matches the print that was left on his daughter Evie's car the night she disappeared.

John and Kevin talk it out and in the process John shoots Kevin.

We next find Kevin coming out of that hotel bathroom.

Kevin puts on his old police officer uniform and gets a call saying there's a disturbance in the lobby. He comes across a karaoke bar in the lobby.

He then realizes he knows the man on stage.

It's the same man he met on the bridge last time he was in purgatory while on his mission to kill Patti.

He learns from the man that the only way to get back to his family is to sing a song. Kevin reluctantly spins the wheel of song choices. Which lands on Simon & Garfunkel's "Homeward Bound."

He gives a chocked-up rendition of the song.

And when he's done, he's back in Miracle with a gun shot wound to the chest.

The karaoke scene is something out of a David Lynch movie: funny, moving, and emotionally charged by Theroux's performance.

Mimi Leder, who directed the finale, said she knew of the karaoke scene back in episode eight because the cast and crew shot some of the finale while they were in that hotel location.

"That karaoke scene was something I was anxious about," Leder told Business Insider. "It was simple - man on stage singing the song - but it was something emotionally we had to get right."

And her star was reluctant to do it.

"Justin was very terrified of singing," Leder said. "He had to do the song more than 10 times. It was several hours of shooting."

According to Leder, she and "The Leftovers" creator Damon Lindelof considered several songs and landed on "Homeward Bound" because of its relation to Kevin's story. In fact, the lyrics "every day is an endless stream of cigarettes and magazines" was so spot-on that Lindelof included shots of Kevin smoking and copies of National Geographic while Kevin hit those lyrics in the song. Both were recurring themes in season one.

Theroux was told eight days before shooting that there would be a karaoke scene. He had around four days to get comfortable with the song.

"And I kept saying to him, 'We don't want you to be a good singer, we don't even want you to sing half-good, we just want you to tell the story of going home in a karaoke bar - in the underworld,'" Leder said.

Leder couldn't be happier with the final scene.

"We worked it until we got to the deep emotion that Justin got to," she said. "He did a brilliant job, everybody was crying by the end."