In “Sirens and the Seductive Power of Costume: Caroline Duncan on Dressing Desire and Control,” we dive into the striking world of Sirens costume design and explore how clothes become instruments of influence, aspiration, and transformation. Costume designer Caroline Duncan walks us through the show’s most unforgettable looks—from the mythic grandeur of Michaela Kell (Julianne Moore) to Simone’s eerie visual evolution (Milly Alcock). With elegance and sharp insight, Duncan details how the costume design in Sirens is never just fabric—it’s a weapon, armor, and a means of seduction.
Spencer Williams: I’m so happy to welcome costume designer Caroline Duncan. Hi Caroline, how are you?
Caroline Duncan: Hi! I’m great. It’s wonderful to be here talking with you.
Spencer Williams: I’m really excited to chat—I binged Sirens in one sitting, and I’m obsessed. Let’s start at the beginning. As you dove into the story, can you tell me about your early conversations with showrunner Molly Smith Metzler about the show’s vision, especially regarding the costumes?
Caroline Duncan: Absolutely. Our initial talks focused on creating a world that felt familiar—think Nantucket or the Hamptons, a kind of wealthy aesthetic. But through Devon’s eyes, it also had to feel uncanny and cult-like.
We aimed to balance a The Stepford Wives vibe with something uniquely ours. Within that, we played with the palette—starting with neutral tones that gradually became more intense and overwhelming as Devon got deeper into her sister’s social circle.
Spencer Williams: Speaking of Devon, I love how you set the tone. The show opens with her in dark, slightly grungy colors, immediately signaling a darker, internal story. She’s clearly down on her luck, which quickly changes once the fruit basket arrives. Tell me your approach to Devon’s costumes? Also Meghann Fahy is incredible in this role.
Caroline Duncan: She’s amazing—such a talented collaborator and actress. Putting Devon in black right away felt right because we knew she’d eventually face off with Michaela, who would be dressed in white. We wanted that clear yin-yang contrast.
We crafted a silhouette that looked worn—like she’d been wearing the same outfit for at least 48 hours, out late partying and drinking hard, then spending a night in jail before coming to this vibrant island with its strict dress code.
We wanted Meghann to look already undone, like she’d been peeled away layer by layer. So we dressed her in layers of black, with a distressed green lace edging on her camisole—an early hint of her seduction by the island’s color world.
We avoided solid black and showed some skin, including scabs on her knees, signaling she’s not taking care of herself. Since Devon has a sexual compulsion, we aimed for a silhouette that communicates confidence in her body—a woman who uses her physicality to get what she wants and the fix she craves.
Spencer Williams: The fruit basket really foreshadows this colorful world at the Kell estate. And then there’s Michaela Kell—played by Julianne Moore. I just love this character. She’s so over the top. Audiences are going to adore her when this streams on Netflix—I just know it.
This must have been a costume designer’s dream. Tell me about working with Julianne and defining Michaela‘s costume design, especially leading up to the gala.
Caroline Duncan: Julie is a dream to work with. She has a clear vision for her characters and brings such grace and elevation to the wardrobe. She’s timelessly beautiful. Together, we built almost all of Julie’s wardrobe, which I think you can tell by the many Grecian goddess-inspired looks throughout the series.
For Julianne, it was about luxe fabrics, movement, and an airy whimsy that leaves the audience questioning her reality—at least in the first two episodes. Devon sees her as both a threat and a hypnotic, otherworldly force over her sister. We leaned heavily into the siren mythology in her costumes.
Starting with that burst of green—a green goddess gown with an exaggerated train we built. Molly and director Nicole Kassell wanted her to feel like she was emerging from the earth as she runs through the forest toward the cliff to release a bird. There’s a nod to Renaissance and iconic Greek art in her wardrobe.
Then, at her home, everything is curated—she’s dressed her staff in similar green tones, creating beautifully composed scenes.
At the first two parties, while everyone else wears wild pastels and patterns, Michaela is the visual pause in white—calling back to cult leader elements, but also evoking toga-like Grecian style. White signifies wealth and privilege—the ability to remain untouched by the world.
But in real life, Julie doesn’t wear silks—that’s not her style. So we had fun creating this goddess-like, aspirational world while still grounding it in what a real woman hosting a gala and fundraising might wear—custom-built and fitting for those spaces.
Spencer Williams: There’s so much to break down. I’m sure people will be talking about her character for months.
I saved Simone for last because she really takes after Michaela —which, personally, I think is great. If this is a cult, it’s one I might want to be part of! Simone adapts to this vibrant color palette but still feels like a personal assistant. I live in L.A., so I know many people who resemble Simone. How did you marry those ideas?
Caroline Duncan: When I thought about Simone, I saw her as the neophyte in the group, just about to be hazed fully into Michaela’s society. She follows all of Michaela’s rules—but a bit more perfectly, with the dial turned up. She’s not a guest at these parties; she’s working for Michaela. So I wanted her to stand apart from the guests but still harmoniously connected to their palette.
Her pink is brighter than everyone else’s pastels—like a pastel turned up. Her hemline is shorter, and we added ’60s-inspired trims to give her a slightly out-of-time feel. We aimed for something Twiggy-esque, playful, and retro. Simone starts the series looking younger than she ends up, so the Sirens costume design needed to support her transformation over five episodes.
Each costume marks a step on that path. The first look is youthful and playful—the least threatening in terms of her potentially taking Michaela’s place. We started with vibrant pink, then moved to a blue shift dress that’s similar in silhouette but more refined. Her character is manic and anxious, unraveling in real time. The bright colors heightened the stakes for Millie’s performance.
Spencer Williams: I love that she’s “turned up” at the beginning—someone the party guests would naturally go to. Accessibility and familiarity were really important. Since we’ve talked a lot about color, I want to dive deeper. Devon turns to Simone at one point and says, “What is this place, and why does everyone look like an Easter egg?” I laughed out loud at that line. How did color play a role in your process for Sirens?
Caroline Duncan: It played a huge role. Before building or illustrating costumes for the three main women, my workspace was covered in fabric swatches and patterns. We often found vendors who provided the same fabric in multiple colorways, which helped with the Fates’ costumes. We leaned into sameness but shifting colors among the three.
We created levels of color throughout the show. Devon’s palette starts darker and more primary—especially early on. The island outside the Kell estate feels like a traditional country club, with Nantucket reds and vibrant blues. But entering the inner circle, the guests’ palette shifts to softer, playful patterns.
Color became a kind of status symbol. We were very specific about the tones around Michaela—especially in Episode Two, which culminates in a Vanity Fair-style photoshoot. Production designer John Paino, director Nicole Kassell, and I worked closely on the image—Julianne Moore and Kevin Bacon center stage. We designed the background, including every guest’s placement and palette.
Every extra was carefully curated. This wasn’t just rental house or off-the-rack stuff—though we used some existing pieces. There was a huge amount of thought and construction in that background wardrobe. I’d say the background became our biggest brushstroke. It painted this kaleidoscope of color on screen and defined the visual world of Sirens.
Spencer Williams: That leads me to my next question. It’s not just the three leads wearing beautiful costumes—the whole island feels curated. I loved the staff uniforms—the sophisticated mint greens. So, what did your department look like?
Caroline Duncan: Lots of extras! I had three assistants. Tricia Barsamian was my right hand, phenomenal with made-to-order pieces. We built most of the three women’s wardrobes and a lot of Kevin’s—his suits were all custom made. The staff uniforms were built from scratch. Tricia and I really were the architects of the world-building.
Heather Breen, from The Marvelous Mrs. Maisel, was instrumental with supporting characters and a lot of the shopping—pieces we found. My third assistant, Sarah Bacot (often my first assistant), spearheaded the background. I told her, “The background is a principal character.” Even though it’s a modern show, we treated it like a period piece for curation and building. Sarah and I have shorthand; she helped gather fabrics, found items, and made boards for silhouettes and palettes.
It was an amazing team of women supporting me. We also had shoppers and a fantastic group who brought this to life.
Spencer Williams: Michaela has a team supporting her, so I figured you had a huge team supporting you.
Caroline Duncan: Yes! Netflix was amazing with support. Once I said, “We have to treat this like a period show,” everyone agreed and gave us the tools to create beautiful things.
Spencer Williams: Let’s talk about Kevin Bacon. He plays Peter, the wealthy husband seemingly running the show behind the scenes. He’s interesting—rich and powerful but also just wants to be left alone in the backyard, gathering quahogs for his Rhode Island chowder.
Caroline Duncan: Well pronounced!
Spencer Williams: Thank you, I practiced! How did you approach Peter? He has a dual personality—loves his lifestyle but also wants solitude.
Caroline Duncan: One hundred percent. JFK was a major reference—we looked at lots of JFK images in Massachusetts. I wanted a classic, throwback American look: generational wealth going back 200 years, Mayflower stock. People talk about “quiet luxury” now, but this is a different version—beautiful items you live with, not replace when they start to fray. You see sun bleach and sand erosion on his Dockers.
His sunglasses might be new every season, but his bisque fisherman sweater is worn year after year at their country house. He doesn’t dress up at home. He wears Crocs—comfy ones Michaela hates—because he’s not peacocking for anyone. He grew up in this world and makes his own rules. Michaela has to create rules to position herself.
His suiting shows the master of industry. He wears a gorgeous Zegna suit to the first party—no tie, much more relaxed than other men. For the finale gala, we built a custom white tuxedo with Gito in New York. I wanted that specific bone color, and a man with that much money would have bespoke suiting, so we honored that with quality and fit.
Spencer Williams: It was perfectly achieved. Every suit made me think, “Okay, I really like this guy.”
Caroline Duncan: Right? He’s pretty likable! He’s not bold. Ethan (Glenn Howerton) is obviously our comedic relief—his dress code is so ridiculous. It’s so over the top, like he got The Preppy Handbook and is following every rule—too far. But Peter doesn’t even have the handbook anymore—he grew up with it.
Spencer Williams: I love a costume montage scene probably more than anyone. There’s a moment later in the season when Michaela‘s loyal friends-slash-followers take Devon shopping for the gala, and we get this montage of her trying on incredible looks. You’re the costume designer—I have to ask about that scene! What were the challenges of setting it up? There were some really great ones in there.
Caroline Duncan: Oh, thank you. First of all, may I say that when we first started to talk about and conceive that moment—what I always call the Pretty Woman moment—I had to figure out how far I thought we should go. To make my pitch to Molly and the director, Tricia and I pulled from so many luxury designers who loaned us pieces, and we had crazy accessories made. We set up a boutique in the production office and held a meeting there. Our amazing production designer John came, along with set decoration—everyone was there. But it was really us presenting what we thought would be the right trajectory for Devon, and it got everyone so excited that that’s what we ended up doing.
It really could have gone in so many different directions, but I saw it as a My Fair Lady sequence—where the hats get grander and more ridiculous. The women—the Fates—the three ladies who are dressed alike and act as little puppets of Michaela, keep saying everything is beautiful, that every piece should go home with her. So we needed some comedy, but it also had to be breathtakingly beautiful.
She is stunning and looks great in everything. Her figure is perfect for the high-end runway pieces we were borrowing, so we were able to show this elevation—how, even as she was looking silly in a lot of these looks, she also looked like she belonged in them.
Her final look—the ombré purple and pink gown you see on the poster—we built that. The idea was: now she’s wearing something that’s actually seductive to her. She feels beautiful in it. It’s her siren dress—her version of what she would have worn to that gala, had she gone with the other two ladies. The ombré gives it a touch of rock and roll and artistry, contrasted with the other two. Then there’s that deep plunge neckline that plays into her sexuality, but it’s still incredibly elegant and feminine. It’s the first overtly feminine look that she truly feels like herself in.
Spencer Williams: That leads us to the gala, which I was really looking forward to. Relationships are really tested in this episode, and Simone makes a head-turning choice. She walks into the gala, arm-in-arm with Peter, and suddenly becomes the new Michaela. It’s eerie. The hair, the dress—it all feels very reminiscent of Michaela. It made the hair stand up on my arms. That final look really spooked me a bit—it felt too similar.
Caroline Duncan: That’s great. I’m glad it brought that feeling out—it was very intentional. In thinking about how to say goodbye to Simone while watching Michaela lose her throne, we knew Julie would be in that marigold, strapless gown. So it felt natural to put Simone in a silvery blue, to create a contrast in what we think of as royal colors.
I loved the idea of Simone wearing this silvery blue because it harkens back to Michaela always being in white—especially in her fencing scenes. We built that gown, and the draping was really complex. We recut it four times. Our incredible tailor Anastasya Jula kept reworking it, because I wanted it to sit just off the shoulder.
The fabric was satin, which was harder to manipulate than the chiffons we used for the other women. But once it came together, the movement felt like ocean ripples or clouds. It was a way to connect Simone to the sky, just like we first connected Michaela to the earth in her green dress.
Again, it’s a siren call. It’s seductive—because she’s about to replace Michaela. But the question becomes: is she going to be any different? Or will she become just another Michaela, ruling with an iron fist—which we know she’s capable of?
We placed Julie in gold opposite her to create that visual contrast. And that gold? It’s starting to tarnish.
Spencer Williams: Yeah. I’ve been thinking about that question all night. I definitely think Simone will be ruling with an iron fist. All the staff were already plotting behind the scenes. Now that she’s back, I don’t think there’s a positive working environment ahead.
Caroline Duncan: Do you think they all get fired?
Spencer Williams: Oh, yeah.
Caroline Duncan: I don’t think Jose can be let go. But…
Spencer Williams: There are definitely going to be staffing changes.
Caroline Duncan: Bye-bye, Missy.
Spencer Williams: Caroline, this has been so much fun. I’m so excited for the world to see this show. What do you hope audiences take away from watching Sirens, and experiencing the costumes, the cast, and this very seductive environment?
Caroline Duncan: I hope audiences reflect on what it means to harness your power as a woman—and what the sisterhood of womanhood is truly about. The show explores how the characters choose their paths, where they make space for sisterhood and female friendship, and where they don’t.
Spencer Williams: Yes, I couldn’t agree more. Costume designer Caroline Duncan, this has been so much fun. Thank you so much for talking with me. I really love the show and can’t wait to see what’s next.
Caroline Duncan: Thanks, Spencer. So good to talk to you.
