Paul Zbyszewski discusses New Eden, Clark Gregg, and the challenges of bringing the series into the station.

WARNING: This article contains spoilers forSnowpiercerseason 4, episode 1, “Snakes in the Garden.”

Snowpierceris back on the rails.

Daveed Diggs, Alison Wright, Roberto Urbina, Kwasi Thomas and Miranda Edwards in Snowpiercer 401

Daveed Diggs, Alison Wright, Roberto Urbina, Kwasi Thomas and Miranda Edwards in Snowpiercer 401.AMC Networks

In a wide-ranging conversation, showrunner Paul Zbyszewski (Lost,Agents of S.H.I.E.L.D.)

discusses the new cast, creative challenges, and highlights ofSnowpiercers final season.

ENTERTAINMENT WEEKLY: How does New Eden shake up theSnowpiercerstatus quo?

Clark Gregg in Snowpiercer

Clark Gregg in ‘Snowpiercer’.AMC Networks

PAUL ZBYSZEWSKI: We started season 3 trying to imagine what this place would be like, right?

So we dove headlong into making this a terrific place to live.

And so life in New Eden is pretty good until Admiral Milius comes rolling in and stirs things up.

Daveed Diggs and Jennifer Connelly in Snowpiercer

Daveed Diggs and Jennifer Connelly on ‘Snowpiercer’.AMC Networks

Now, aboardSnowpiercer, different story.

Who are these guys?

What do they want, and what do they want with Liana?

You worked with Clark Gregg onAgents of S.H.I.E.L.D.What does he bring to the role of Milius?

He’s a real force of authority.

Someone who’s flawed, but to what degree heknowshes flawed remains to be seen.

And I knew from personal experience that Clark could deliver on everything we asked him to do.

He’s an immensely talented actor.

He’s a great fit for the role.

What can you tell us about Michael Aronovs new character?

Michael Aronov brought all of that and then some.

Hes an incredibly talented performer I mean, he’s got a Tony Award!

credit to Wittney Horton, our casting director, for bringing him to us.

Michael, he’s a five-tool player.

The Animal Squad brings an extra layer of tension to character dynamics that are already quite tense.

What motivated bringing in this new set of characters for the final season?

They came from necessity more than anything else, and it starts from character.

What would they look like?

So that animal squad came from necessity more than anything else.

What surprised you as you constructed the narrative of this final season?

The weight of having to satisfy the arcs of all of these characters.

Having to satisfy that times 15 or 20 was a massive challenge.

Do any character arcs stand out as personal highlights or favorites for this season?

I can’t pick just one.

It’s like choosing one kid over another.

You grow to love all these characters and you put as much time and effort into all of them.

I will say that just the arc of the show and where it lands in the finale was satisfying.

It was a sense of, Okay, we started with something.

But again, the audience will tell us whether we came through or not.

How does this last season differ from the previous ones?

People can walk left and right instead of just forward and back!

The show really is markedly different because of the existence of New Eden.

Now that those obstacles have been removed, it completely changes the game for the people in New Eden.

Their energy levels went up because they felt like they were on a different show.

It was like, Wow, this is not what we expected.

This interview has been edited for clarity and length.

The season 4 premiere ofSnowpierceris now streaming on AMC+.

The show airs weekly on Sunday nights at 9 p.m. ET/PT on AMC and AMC+.