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Carrie Coon has a way with words. And when she learned she had to deliver an eight-minute monologue in the series finale of The Leftovers, she knew exactly what she had to do.

"I approached it the same way I approach any play, really: You have to learn the lines," Coon tells "For me, it was a matter of getting the lines down cold, so I wasn't thinking about them, and thinking of it as a night in a theater that you were going to do 12 times in a row, which is basically what working on TV is. You learn the lines so you can show up on the day and be really available."

Coon received the script a few weeks in advance in order to prepare the monologue — the crucial linchpin in which Nora reveals to (ex?) lover Kevin (Justin Theroux) what she had been doing in the decade-plus since their brutal hotel room fight (in Season 3's "G'Day Melbourne") and what had happened to the 2 percent of the population that disappeared (before the very first episode of the show). Or what may have happened.

Like all great Leftovers moments, Nora's tale is grand, intimate, bizarre, unexpected and moving. She says she went through a machine and woke up in an inverted reality where the missing 2 percent is living in a mostly barren world. She says she found her kids, now teens, and her husband, now remarried, all happy, so she decided to return. She says she never told Kevin because she was afraid he wouldn't believe her.

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The whole time Nora is speaking, we never see this alt-verse — a purposeful choice to underscore the ambiguity the show trafficked in and because, ultimately, it doesn't matter if her story is true.

"Some people have talked about how in the past when you see monologues in shows — our show, other people's shows — you see flashbacks," Coon says. "You see the person actually going through that story to supplement the language. In the case of our finale, all you have is Nora telling the story without any flashbacks or imagery, except for the memory you see earlier in the episode."

<p>Carrie Coon, The Leftovers </p>

Carrie Coon, The Leftovers

That Nora's story is so powerful and believable is not just a testament to creators Damon Lindelof and Tom Perrotta's prose but Coon's commanding, quietly volcanic performance. Her face cycles through a hamster wheel of emotions — fear, rage, pain, grief, shock, anguish, regret, love, and eventually, relief when Kevin says he believes her — as she cautiously, deliberately recounts the adventure of a woman we've known as stubbornly pragmatic.

Coon's magnetic ability to paint a vivid world with just words outranks any fantastical sequence that could've been filmed. The mantra is "show, don't tell," but when you have Coon's assured, compelling verbal brushstrokes that were honed in the theater, where the written word does the heavy lifting, there is no need — never mind the intention to remain vague.

"We've actually found in talkbacks with audiences... It's about 70 percent of the audience believes her and 30 percent says, 'No way,'" Coon recalls. "If you were to put images of Nora acting out that story, that takes away the ambiguity. Then it implies truth, certainty. And our show's never been particularly invested in objective truth."

The Tony-nominated actress decided for herself whether Nora was telling the truth. "And I'll never tell," she says — nor does her arresting performance betray it. That's not to be coy or because she doesn't want to affect fans' interpretations, but because she wouldn't have played it differently either way. The Leftovers was never about the missing 2 percent. It's about coping with unfathomable grief and tragedy, the stories we tell ourselves and each other. It's about believable, beautiful lies that, like a nun (Linda Cropper) Nora befriends says, make for a "nicer story."

"You can't play ambiguity; you can only play a choice. I did play a choice. I know the choice that I made and I played that out as fully as I possibly could because I had an objective, which was to convince Justin of my truth," Coon explains. "And in some ways I don't think — no matter which choice I made — I don't think it would be different the way it actually ends up on the show, because it's a fascinating thing about human beings and what we're able to do. ... Human beings are really, really good at telling our stories so effectively and so often that we believe them."

Coon had to tell Nora's story over and over again during the day of shooting. But she credits Theroux for doing the harder part, in a sense, of absorbing and silently reacting to Nora's tale each time, as if he had never heard it before. Theroux was on set with Coon for every iteration of the monologue, which was vitally important because from Coon's perspective the speech isn't even about Nora's story, really.

"That scene is not about me; it's about Kevin. It's about convincing Kevin of something," she says. "Justin is such a wonderful scene partner. He's always so open and available and brave and honest in his own work. You know he's there with you, encouraging you in your own honesty and bravery and all those things."

After the last take, there was relief, exhaustion, but more work to be done: Theroux's preceding monologue from the episode still had to be filmed, along with the final wide shot of the pair sitting inside Nora's cottage, crying, hands clasped. That shot wasn't scripted, but the two still had plenty to say.

"I'm pretty sure we grabbed that shot after I had finished doing the monologue many, many times, maybe even after Justin had done his coverage," Coon says. "And we were probably just going, 'I'm so glad that's over. I'm glad I don't have to do that anymore.' 'Yeah, me too. It was getting old.' 'Do you think we'll have enough time to do your monologue?' 'Hope so. We're losing the light. Oh, no!' That's probably what was happening in it."

The Leftovers series finale is currently available free to watch (for a week) on HBO's YouTube channel.

Additional reporting by Alex Zalben