Spoiler alert: Do not read unless you’ve watched episode 207 of “The Leftovers,” titled “A Most Powerful Adversary.”

Kevin Garvey had a very “hard day,” just as the oh-so-cruel Patti Levin warned him. Last Sunday’s episode of HBO’s “The Leftovers” ended with a dramatic twist that left him seemingly dead — and shocked fans reeling. Justin Theroux talked to Variety about Kevin’s “drastic” decision.

How does this season compare to last season for you?

I’m loving this season. I was loving making it. The scripts we were handed just kept getting better and better. Not that the source material (for the first season) was bad; it was exceptional. It was just something nice, for (creator) Damon (Lindelof) and for Tom (Perrotta), too, to be let off the leash and explore some other themes.

What did Damon and Tom tell you about what would be in store?

Just the geographics — where we were, why we were going there. And not much else. I didn’t really ask. When we were doing the first season, we had the book, but that took lots of departures and went down different roads that the book didn’t mine as deeply. This season, Damon just said, we want to go to this miraculous place and stay there. In a weird way, even though the world gets bigger, we want to make the world smaller and still be able to work out all these large themes.

Is Kevin “sane” at the start of the season? What’s his mental state?

At the beginning of the season, I think he’s in a good place. But his secret we learn about Patti is the motivating force to get him out of New York. I think he thinks he can wrap his arms around his problem. He’s more confident about it the beginning of the season. Obviously that starts to spin more out of control for him.

Was that the reason behind his move?

I think he wanted to pull a geographic and forget that his dad was so messed up, forget that he had a wife in a cult, forget that his son won’t speak to him. “If I just pull up and move, that American ‘go west, young man’ mentality. But problems go with us when we move.

What triggers his meltdown? Is it Patti’s relentless onslaught?

He’s in a sustained meltdown. He’s not getting a job anytime soon. His house isn’t getting fixed up, aside from doing minor home repairs and going to the hardware store, and spending a lot of time in that truck talking to people and trying to figure out how he got there. But I think what he enables him to kill himself is feeling that as much as possible, he’s been able to tack down his family in a way. He’s gotten somehow Laurie back to his house with Jill, even though that’s maybe not the best relationship. He’s gotten a promise from Nora saying she’ll come back if he can rid himself of these voices. And so he’s put his finger in the dyke long enough for him to run to Virgil’s trailer to try this thing. I think he thinks he’ll be back in 5 minutes, as Virgil promised.

Why does he believe Virgil?

It’s a move of desperation. He wants the cure quickly, whatever that is. He’s not willing to admit he’s his father. He’s not willing to go a psychiatric facility and take medication and nuke himself. It is drastic times for him so drastic measures. Why he has such faith in Virgil, I don’t know. Whether Virgil’s clairvoyant or not, Kevin believes he’s got something from their encounter in the visitors center in the first episode.

“The Leftovers” straddles the otherworldly world and the real world. Which side does Kevin fall in?

Different characters are affecting and pushing the stories in different ways. Nora’s obviously a very proactive character in things she does, actions she takes. If it wasn’t for Kevin’s family and his house, he’d easily be the guy you see on a street corner crying and yelling at someone. Or yelling at no one. I don’t see him as a sci-fi character. He’s more of a put upon, affected person who keeps getting pushed in more uncomfortable corners.

Aside from the initial scare from the first time she appeared, the more real she becomes. In the last episode, she slapped him. So now there’s physical danger involved. At a certain point, you go into self-preservation mode but you want to preserve the sanctity of your family. He is very worried about both his daughters, his girlfriend, and that tension is untenable. You’re seeing dead people, you agree to be handcuffed to the bed —  your life is not your own anymore.

Nora seemed fine with everything — until you confessed to her.

She’s a force of nature. I think she does run that show in that household. They’ve reversed roles. She buys the house. She’s a more proactive person in the household. She tells it like it is and what she wants. I think he probably underestimated her own personal trauma from losing her whole family. No one can really wrap their minds around that. It’s an incredibly complicated relationship. I remember reading the script and wondering, why would your first reaction be to flee? She takes what is her newly cobbled together family with her, which is interesting. She really think she can start over again.

But she leaves Jill behind!
Poor Jill. She’s the only sane person in the house.

Is Kevin a good father?

He’s trying his best. He’s trying to pair that against his own wants and desires. In the first season in episode 9 when he had it all, he was questioning whether that was enough. Then he realized at the end of the season, yeah, all you really need is your family. And by then, he’s been saddled with mental issues and it was too late.

Too late indeed, given the last time we see you lying on the floor in Virgil’s trailer. What was your reaction when you read that death scene?

Yeah, I was worried. It’s an incredibly alarming thing when you read that on the page.

Will we see more of you?

It’s possible you’ll see more of me in a couple of iterations, but that’s all I’ll say.