When drugs and alcohol are involved, it can be difficult to keep things straight.

Eve Hewson learned that lesson in nitty-gritty detail while making the new historical drama The Luminaries (premiering Sunday on Starz). Her character, Anna Wetherell, becomes ensnared in the grip of several drugs, including laudanum and opium, after traveling to New Zealand in pursuit of gold. Her various states of intoxication got so complex that Hewson had to devise a tracking system.

"One of the things I was mainly confused about was just which drugs I was on at what time," the actress tells EW. "I had this really nice house in New Zealand, and on my kitchen wall I mapped out the entire show, every scene on notecards. I had my notecards color-coded with orange is for laudanum, then pink is for opium, blue is for hangover, green is for sober. So I could track what I was going to be doing in the scene, how loose I was, how sedated I would be, all of those things."

Hewson's character's state of sobriety, or lack thereof, is just one of the complicated threads of intrigue running through the series.

The Luminaries, which is based on the Man Booker Prize-winning novel by Eleanor Catton, follows Anna and Emery Staines (Himesh Patel) as they arrive in 19th-century New Zealand with the intention of digging for gold. When the scheming Lydia Wells (Eva Green) intervenes in Anna and Emery's plans, Anna ends up embroiled in a plot that ends with her implicated for murder. The series, which Catton adapted for the screen herself, jumps back and forth in time, working to uncover the mystery of who really killed Crosbie Wells (Ewen Leslie).

We chatted with Hewson about what it was like filming in New Zealand, how she crafted a believable connection with Patel given so little shared screen time, and more.

ENTERTAINMENT WEEKLY: Had you read the book or were you familiar with Eleanor Catton before signing on?

EVE HEWSON: I'm ashamed to say that I wasn't familiar with her work. But I read the scripts. Actually, it's a stupid story, but they sent it to me and I read it really late at night, and I thought that the whole first episode took place on a boat. I think I was jet-lagged or something. Then when I actually woke up and came to, I read the script and it was so unique and so beautiful — the characters, the love story. It was just really stunning. When I started talking to Claire McCarthy, the director, that's when I started reading the book, and then I told some friends that I was going out for it. So many of my friends loved this book. That made me excited, because everyone was really excited to see it.

The Luminaries
Credit: Anna Wetherell/Starz

Eleanor has pivoted somewhat from fiction to screenwriting, adapting this and last year's adaptation of Emma. How much interplay did you get to have with her, and did she help you shape the role?

Yeah, she was really present. Eleanor's really cool. She's a very, very fun person, so I just enjoy her as a human. But she was around for most of our prep. I did like three or four weeks of rehearsal. The script was evolving every now and then, so she was in and out of set. We had a lot of time to hang and talk about Anna, but she was so generous with Anna. She was just like, "You've got this. You're Anna, just do it." She didn't really have any notes, which was very kind.

What appealed to you about Anna?

The thing about Anna that I fell in love with was that at the beginning, you meet her and she's an enigma. She's very unknowable, and you don't know where she's coming from. I don't think you fully believe her story that she's in New Zealand to dig for gold. There's some mystery to her. As the story goes on, you learn that she's a dark, quite disturbed character, and she's running from something and you see her fight against herself. She comes up against all these characters in the story, and they're trying to make her something. Older men are trying to take something from her, they're projecting their fantasies on her: They want to make her the prostitute, they want to make her the daughter, they want to make her the wife, whatever it is. You see her succumb to that pressure, but then slowly rise out of it and choose herself and choose hope and choose love, and I thought that was a really powerful arc.

Setting is a character unto itself here. Had you been to New Zealand before? Can you talk about how that impacted your work?

I've never been to New Zealand. I went off for six months. I remember saying goodbye to my sister outside my apartment in New York, and I had my plane ticket that said something like, Oct. 20, and then my return ticket was like, March 30. I remember thinking, "Holy crap, this is going to be a journey." It ended up being a really beautiful, peaceful setting to do some really f---ed-up work. Having to play Anna in the depths of despair and and all the things that she goes through, but then being able to spend my weekend sitting out on my porch having a cup of coffee and listening to these tropical birds, it helped me recover. The landscape and New Zealand is a huge character in the story, but I spent a lot of time in a studio, not seeing a lot of New Zealand, which is a bummer. Most of the guys had more time off, and they went and traveled. But when we were doing exterior stuff… it was like the air got me high, and I was so excited to be outside in this amazing place. I was just running around like a lunatic. It was so joyful, like those moments where you can't really believe that it's work.

The show plays with time jumping between her first arrival in New Zealand and several years later, when she is a murder suspect and at the heart of a mystery. What was it like jumping back and forth between those poles? You had your notecards, but was it particularly challenging or confusing?

Those really helped. But we shot it by location, so that helped. It wasn't like I had to be fresh-faced in the morning and then a dug addict at night.

Anna immediately has this romantic connection to Emery, which seems to take on a spiritual level in the flash-forwards. How did you make sense of that, and how did you build that connection with Himesh when you don't share much screen time?

It's such a funny thing. The whole story makes or breaks itself based on their meeting. That is the kickoff point to them going on their journeys and then coming back to find each other. So we were all nervous to get that right. But what's ridiculous is Himesh and I met, and obviously most of our story lines aren't together, so we didn't work together for about three or four months into shooting. But we ended up becoming really good friends because we were hanging out on the weekends and whatever. So that first scene on the Fortunate Wind was actually the last scene that we shot together on the last day of the shoot. It was perfect. We thinking the entire time we were shooting, "God, if we don't get that Fortunate Wind scene good, we've screwed up the whole point of this." But we were so comfortable with each other; we had a natural chemistry there that ended up selling it.

She is very much a woman bound by the limitations of her era. Seeking a new life, she is immediately thwarted by a woman who cons her and uses her for her own gain. Did you find threads in her story to women of today?

Absolutely. It's so relevant. She is quite a feminist character. It was easy to understand that —just being a woman, being an actress, and feeling like you have to fit into a certain way of being as a female. I really enjoyed playing her and feeling her pain and suffering, but then also fighting back. Allowing love to take over and believing in hope is really important for women. I think women will really enjoy watching this show because of that aspect, but it's also just important to tell stories like that and show that this has been going on for centuries. It's an old trope that women have to consistently revisit. It's important to watch someone fight against that and then come out of it, strong.

This interview has been edited for length and clarity.

Related content:

Comments have been disabled on this post