'Hell on Wheels' EP explains recasting of Cullen's bride—FIRST LOOK

Hell on Wheels returns Aug. 2, and the AMC Western—which parlayed Saturday night success into an expanded 13-episode fourth season—will have more than one new face. One that might surprise fans is that of Cullen's young Mormon bride, Naomi. Originally played by Siobhan Williams, the character was introduced early last season when the railroad carved its way through her family's Nebraska homestead. Cullen (Anson Mount) had sex with her once in the barn, but then had to hang her brother after her trigger-happy father blamed his son for killing of a member of the railroad police. In the season 3 finale, a kidnapped Cullen avoided being hanged by the Mormons (and masquerading Swede) at Fort Smith and married Naomi, who he'd learned was carrying his child. Canadian actress/singer MacKenzie Porter steps into the role for season 4. Here, showrunner John Wirth explains the switch and teases what's to come.

ENTERTAINMENT WEEKLY: Why was the part recast?

JOHN WIRTH: We start where we left off. As you can imagine, having left Cullen in a place where he married this young woman and had a child on the way sort of predicated the kind of story we needed to tell this season. We found ourselves in the unfortunate position of having lost our actress: Siobhan Williams went to another series [ABC's Black Box], and we got into some scheduling conflicts, and we were unable to bring her forward. We were kind of desperately considering how we should handle this: Should we recast? Of course, whenever you have that conversation, the two Darrens situation is always brought up. It was not my first choice, but we went ahead with it, and I think we were really lucky to get MacKenzie. She's a helluva actress and has really grabbed onto this part and brought a soulfulness to it. As matter of fact, I was standing on the set [June 19] talking with Anson about it, and my first expectation was that his character would marry her out of a sense of honor. We've established a pretty strict moral code with him, which doesn't preclude him from shooting people in the head when they need it but would preclude him from walking out on a woman in that situation. So I was fully prepared for his position being, "I'm doing this out of responsibility," because he's a Southern gentleman. And what I've been surprised by in looking at the film is that there's a growing intimacy there and possibly even a love affair happening between those two characters. The baby is born, and we see him interacting with the baby, and I think he's surprised at how he's feeling about them.

What will we learn about Naomi?

The fascinating thing about Naomi is that she is a very good Mormon woman, and she's very clear about her position in the world as being a Mormon and a Mormon wife. When she comes up against some of our other characters, some of whom are pretty forward-thinking for 19th-century women, we end up with some pretty interesting drama that we're playing. There's a bit of naïveté there, and yet because she was born and raised in the wilds of Nebraska, there's a toughness and grittiness to her on the inside, which is wrapped in this sort of sweet and caring outside.

Let's go back to the sex scene in season 3.

The uncut version was actually much more entertaining than the AMC officially approved version. But you'll have to come over to my house to look at that version, if you want to see it.

Siobhan Williams is in her 20s, but she played much younger onscreen, which made the scene slightly disturbing for some viewers. Did that catch you by surprise? One benefit of having to recast, I would imagine, would be the ability to address that.

Well, one would think. However, here's what happened. I think Siobhan is 23 in real life, and we were playing Naomi as 18. She did look a lot younger, and people, when they were watching the show, thought he was robbing the cradle a little bit. And also, I think she's about 5'3″ and Anson's 6'1″. Where we got caught kind of flat-footed—and this did surprise me and it surprised everybody—was in the barn scene, when she came up next to him and he was brushing his horse. When you had her standing there next to the big horse and next to this tall man, she looked like a child. We ended up editing that scene so that we could kinda get around that sort of thing. And then when we went to recast, I thought, "Okay, now's our chance to cast an older actress who's taller, and we'll get out of that problem." And as it turns out, MacKenzie is about the same height and is exactly the same age. She plays a bit older, I think. But when we were doing music spotting the other day, Kevin Kiner, who does the music for us, said, "Boy, Naomi's changed a little bit since last year." I said, "Yeah, she's a year older." He said, "Amazing." I said, "But you know it's a different actor, right?" He said, "What???" [Laughs] He couldn't tell.

Anson explained to EW why he thought the barn encounter was so important [it's realistic that Cullen would have urges, and him having to hang her brother the next day showed his ambition and priorities—"He has to get on with the railroad"]. What was the thinking behind Naomi's pregnancy?

When we came in to convene the writers' room originally [for season 3, fellow EP] Mark Richard said, "I have an idea that Cullen ends up in a Mormon fort at the end of the season." We had no idea what that meant. We kinda had a sense of where we were going, but we didn't know the details. Then I wrote the episode where he met Naomi. One of the things we try to do in every episode, and certainly we tried to do it last year, is that for every action there's a pretty serious consequence. So we thought that this would be the perfect situation where he would have a fling, it lasted a few minutes, was probably forgotten a few minutes later as he went on for the rest of his life and the railroad moved West—and then one day the consequences of those few minutes come back to haunt him in a big way. That's really the concept. We knew that she would get pregnant and he would come back into her world very early on in the season last year, once we figured out what the Mormon fort was going to be. But it is interesting how you start out with an idea and the story sort of carries you, and it doesn't always go in the direction that you think it's gonna go.

For more Hell on Wheels season 4 scoop, come back to Inside TV on June 26.