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[SPOILER ALERT: Read on only if you have already watched Sunday’s “Now” episode of

Aaron loved to show photos of Alexandria to potential recruits. But when he lost his backpack and those photos fell into the hands of the Wolves, the results were disastrous. Aaron’s guilt over the slaughter of fellow Alexandrians led him into the sewer as he offered to help Maggie past the walkers in an effort to track down Glenn and the others. The plan didn’t work out, but showed a man ready to take action in the face of mounting adversity.

We also saw a man ready to stand up for Rick in the wake of town criticism over his aggressive approach to rid the area of walkers. We spoke to actor Ross Marquand to get his take on Aaron’s big episode and, naturally, the murky fate of Glenn. (Read through both pages for the entire interview, and also make sure to check out our interview with Lauren Cohan.)

ENTERTAINMENT WEEKLY: Let’s start with the big speech that Aaron makes at the start of the episode at this impromptu town meeting by the wall, and I want to take the first half of that speech first. In that first half you talk about the herd in the quarry and how “The plan that Rick put into place stopped that from happening. He got half of them away.” There is a lot of doubt among the Alexandrians about Rick. Why is it important that Aaron stand up for him there?

ROSS MARQUAND: We’re just looking at the devastation of the entire township and we’re saying, “Oh, well, that just went horribly wrong.” Especially for the Alexandrians who didn’t go outside the walls and didn’t participate in the plan — they’re certainly having doubts echo what Carter was saying in the first episode of the season, which was, “Is there another way we can go about this? It seems a little risky to try and divert literally thousands of walkers and try to create this parade of death right along the road of our township.” He’s trying to let the other Alexandrians know that the plan didn’t go as planned, but even though the threat is now right outside the walls and it seems hopeless, it could have been so much worse had he not done this plan. And it was only a matter of time before this came to our door.

Now let’s take the second half where Aaron talks about losing his pack and the photos that led the Wolves to Alexandria. Aaron takes responsibility for that as you say, “Those people who attacked us, they found their way back here because of me.” How much blame is Aaron putting on himself here for what went down?

He puts total blame on himself. And as a viewer, I disagree with that sentiment because it would be very difficult for the Wolves to look at these pictures — especially without any people in them and with no directions included inside the backpack — and be like ‘Oh, yeah. I know where this place is!” But somehow they put two and two together, and by looking at those pictures they have either passed this place before or constructed it in their minds that this is clearly a place they want to take.

And whether it’s by following Aaron, Morgan, and Daryl back, or by the mere fact that they had seen something like this in their travels, they’ve decided now, of course, that they’re going to take this by force. So finding that backpack, however flimsy the evidence is that it’s his fault, he still feels completely responsible for it and he beats himself up. And that’s what motivates his actions for the rest of the episode.

Yeah, let’s talk a little more about that because clearly we know why Maggie wants to go out to find Glenn. Why does Aaron insist on going with her? Is it just feeling restless after what happened and needing to do something to make the situation better?

It’s a restlessness brought on by complete guilt and shame. That’s really the motivating factor for him moving forward is just that he feels so responsible — not just for the people of Alexandria, but for Rick’s group too. He’s the person who brought them into the walls in the first place. He’s responsible for them. He’s not going to feel good about anything that’s happened with the loss of life and destruction of the township until he can go out of his way to make amends for it.

And the best way that he has found to do that is when he finds Maggie sitting by the pond and puts two and two together and realizes that she is going to go out and look for Glenn, so he aligns himself with her and says, “Look, I want to help, I’m not trying to be a wrench in her idea. I really want to go out there and help you.” And it’s pretty clear as time goes on how risky that idea really is.

Let’s talk about that sewer scene. What was filming that like?

We have the best crew. What they were able to do constructing that sewer — it was the entire length of the soundstage. They basically created a loop onto itself and they cut away certain sections so it would be easier to film and wanted to make sure there would be areas were you were in literally two feet of water, because that’s what the script called for.

It was absolutely disgusting because they ground up candy bars and oatmeal and paint chips and egg whites and egg yolk. It looked just disgusting — just the mass of God knows what ground up and thrown in there. It was perfect because as soon as Lauren and I stepped in there we’re just immediately taken to that world. At no point during the filming of that did we think, “Oh no, we’re not actually in a real tunnel.” We thought from the moment we stepped into it that it was the real thing.

It was so much fun. It was one of my favorite episodes to shoot so far, truthfully. It was really intense at parts because even though we had this real working sewer system, it was also a lot of sharp edges and jagged spots, and also some tight corners to film in.

I remember when we were doing the scene where we’re dislodging the ladder and it comes back and hits me in the head and I fall back, each time I had to kind of tailor how I was falling back because each time I came up on the wall there were some sharp points there. So I wanted to be really conscious of not just making the stunt look right, but also not bashing my head. They ended up using what they could from that and then they had a stunt guy do a fall from a different angle where he could just go for it, which was great.

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