Spoiler warning: Do not read on unless you’ve seen “The Walking Dead” Season 6 finale, titled “Last Day on Earth.”

The Season 6 finale of “The Walking Dead” literally brought Rick Grimes to his knees. And for Andrew Lincoln, it wasn’t a pleasant experience.

After a full season of teasing the arrival of arch-villain Negan (Jeffrey Dean Morgan), showrunner Scott M. Gimple and crew delivered a chilling introduction that built to the death of one of nearly a dozen key characters from the show. But who Negan actually killed in his first scene was left up in the air — a secret the show will try to keep until the next season starts up in October.

Variety spoke with Lincoln about filming the scene, why he said the finale’s script made him “physically sick,” parallels between Rick and Negan and how the cast handled another loss from their ranks, without knowing who they were mourning.

Excellent work on the finale. What was it like filming that climactic sequence?

It was a pretty traumatic and intense and weird two nights. It’s an astonishing scene and I thought Jeffrey Dean Morgan was just magnificent and magnetic in it. But also it was the first time I had felt a sense of unity and focus and intensity from everybody. All around the camera and also from the entire cast — I hadn’t felt like that since Season 1. It was a really exciting atmosphere on set. I think everybody realized that we had to rise to challenge and create this suspense for the scene to work and the episode to work.

Was the final moment scripted as a subjective POV shot from the beginning?

Absolutely. It was scripted as a POV.

How did the cast react to the script? Did everyone come together and say, “What’s going on? Who is it going to be?”

There’s an unspoken feeling on set when we know somebody’s dying. We link arms, bow our heads and pull each other through it. I suppose that’s what they call omerta, the code of silence in the mafia. We have our own code of silence in “The Walking Dead.” It’s so intense and so traumatic to be losing a friend. It’s not just a professional relationship, it’s a personal relationship. So we all decide to not talk about it when this happens.

But this is the first time where it happens and yet you don’t know who it happens to. Did that change the feeling on set at all?

No, because you know that it’s over. The intention is exactly the same. You know that one of us is dying. The moment that Rick gets to his knees and acquiesces and almost hands the crown to Negan, it’s done. I was very consciously trying to position Rick in this place where all he’s fought for and killed for these last few years has been smashed all around him in that final scene. I don’t think it altered anything, the not knowing. Because we’re absolutely convinced that the game is up.

I know you don’t watch the episodes, but did you sneak a peek at the final shot just to see how it looked?

I did watch the final shot. I watched them do it. A lot of us waited behind because Jeffrey had done such an extraordinary job, to land such an incredible speech and entrance and create such an incredibly tough, charismatic character in front of our eyes, even though I was drilling hell holes into his soul the past two nights. I thought it was the least I could do to watch his final shot, which was particularly badass. So yes, I know how it finished.

You said reading the finale made you “physically sick.” Now that we’ve seen it, what specifically did you mean by that?

I think it was the frustration I felt that I play this man who had answers to every available situation up until this point. I felt just powerless and frustrated and thwarted and angry and all of the things when I was reading it. It made me so upset. I think I was feeling all of the things you’re supposed to feel when watching it: It’s over. Everything [Rick] stood for is over. It hurt me, reading it. It hurt me, because he also feels responsible. He’s put these people — through his own pride perhaps or single-mindedness — he’s put everybody’s life in danger.

I’m so used to playing someone who had a way out or had an answer and I had to play a man who got to his knees. The joy of playing Rick has been trying to finely calibrate what it is to be a leader. He saw a problem, worked it out, makes mistakes, recalibrates and then that works for a time. This felt like a demolishing of all of this work that had happened over six years. [Negan] has got a baseball bat and he’s smashing everything I’ve fought for.

Even now do you or anyone in the cast know who will die?

Because it’s too painful and too intense, we made a pact on set that we won’t speak about it. I apologize but I can’t talk about it.

Have you spoken at all with the producers about how the show plans to keep it a secret or have they discussed anything about that with the cast?

That’s the double edged sword of our show. As a victim of our success, people are very keen to know what happens next. We’ll try our damndest [to keep it secret] because it’s such an important and powerful moment that changes the landscape of “The Walking Dead.” It would be a real shame if it got out.

It’s an incredibly courageous way to start a season. It’s not a conventional way of opening a new season of our show. Usually it’s an up-and-at-’em call to arms, big episode. This is a brutally damaging, psychological and emotional battering to begin Season 7, which is a huge writing task. It’s an extraordinary call from Scott [Gimple]. I commend him. He made a pact a few years ago to keep scaring us because it’s absolutely the right thing that we should be doing after five years. I’m a bit scared about playing this guy, but that’s a good thing. It means we’re challenging ourselves and pushing ourselves. We’re trying to do something to not repeat the show and I think he’s done that with this way of starting Season 7.

You mentioned it’s an unconventional ending for the show and a lot of fans are very upset that the death was presented as a cliffhanger. What would you say to fans who feel like this is a stunt?

I think people are absolutely in their right to feel exactly what they feel. The mere fact that there’s a lot of energy around people feeling means that they’re invested in the show. I always want to go to the movies and watch something and be moved by something or feel things. I know that is the great endeavor in our show: To keep people invested emotionally in this story.

I prefer to not talk about how the season finished, but how we are endeavoring to begin next season. I think that’s a truly impressive and quite courageous call from Scott, which is something I’ve grown to expect from a guy who pushes himself harder than anyone else I know because he cares so much about his show.

There have been parallels drawn on the show and outside of the show between Rick and his group and Negan and the Saviors. Do you feel those are fair? Can Rick claim moral superiority in any way?

I do think it’s a comment on the world and what it does to people and what leadership now looks like in these very bleak brutal environments. I do think there’s a brutality to Rick that is not his natural way of operating as a leader. It’s only brought into account when he is threatened or the people he loves are threatened. It’s not about coercing others into living the way he wants you to live. It’s not a dictatorship. He’s a much more benevolent [leader] but if he feels threatened, as he did by the Saviors, and he knew that the only way to eradicate that threat is by killing, then he’s not afraid of doing something that actually appears morally questionable.

I do think he was full of hubris. I think after the battle for Alexandria he believed his own hype and he said a couple of things that were pretty grand statements. Maybe that weakness in his leadership, his pride, made him make a call that was questionable. And Morgan’s restraint was perhaps the right call.

But he knows there’s a modus operandi with these guys that one person is going to get killed. Rick’s feeling was that he doesn’t want to risk one life for the sake of preserving the integrity of Alexandria. He’s not willing to live under a rule. This is a question that I know, I’m sure, is going to be explored absolutely in the next season, which is thrilling. It’s the mirror put up against Rick. One of the great things about playing a guy for six years is it feels like I’m trying to explore who and what the perfect leader would look like. I think Rick has made many good calls over the six years that I’ve been living with him but also he’s made bad calls and those all recalibrated who he is as a man and as a leader. I think what happened and is about to happen at the beginning of the next season is going to change irrevocably who this guy is from now on. That’s if he makes it past the bat…

There are many similarities between [Rick and Negan], but I do think there is morality still in Rick. It’s morals and the sanctity of the people who he loves and fights for that are the driving force behind his decision-making. He is a ruthless, uncompromising and tenacious man who will stop at nothing — we’ve seen it — to keep these people alive. But I think he’s met his match.