Zac Posen (Photo by Amy Sussman/Getty Images)

Designer Zac Posen has mastered the art of the fashion pivot. After shutting down his eponymous label in 2019, the man behind many memorable red carpet moments has continued to design wedding gowns, launched a gender-neutral engagement ring collection, and collaborated with the New York City Ballet. Now, he’s making his next foray into costume design with the upcoming film, The Outfit.

Known for his sensationally designed gowns as well as his masterful tailoring — honed during his tenure as the former creative director for women’s collections at Brooks Brothers — Posen was the perfect man to tap for this film, whose main character is an English tailor who worked on Savile Row. Posen acted as the fashion authority for co-writer and director Graham Moore’s bespoke Hollywood crime flick, and worked alongside the film’s London-based co-costume designer Sophie O’Neill.

Mark Rylance in Graham Moore’s The Outfit, a Focus Features release. (Courtesy of Nick Wall / Focus Features)

The movie stars Dunkirk’s Mark Rylance in the titular role of Leonard, an English tailor who works in mob-centric 1950s Chicago. Making suits for gangsters, Leonard and his assistant Mable (portrayed by Zoey Deutch) find themselves in a precarious situation when the local crime families make themselves at home at the tailor’s shop, while law enforcement also pays a visit. Rounding out the cast with Dylan O’Brien, Nikka Amuka-Bird, and Johnny Flynn, the film (in theaters this Friday, March 18) takes place over the course of a single high-stakes night.

Posen explained his involvement in the film, telling Vogue that Moore reached out with questions regarding the authentic process of suit making. Bringing expert tailors from Huntsman on Savile Row such as Campbell Carey on board, Posen called upon their expertise for the film. “I had this crazy idea that Mark [Rylance] could job-shadow the master cutter there,” Posen said. “For two or three weeks before production he went in and started learning and watching the trade of those master cutters and how they put a suit together and he became part of making the costume that he wore.”

Zoey Deutch and Mark Rylance in Graham Moore’s The Outfit, a Focus Features release. (Courtesy of Nick Wall / Focus Features)

He also described the process of working with O’Neill while oceans apart amid the COVID-19 pandemic, approving swatches, hat variations, and different tie fabrications over Zoom, and what it was like designing for on-screen characters instead of the actors themselves. “What was really cool for me was to see how clothing has a transformative quality in the filmmaking process to support the actors and their performance,” he said.

Dylan O’Brien and Zoey Deutch in Graham Moore’s The Outfit, a Focus Features release. (Courtesy of Nick Wall / Focus Features)

On whether or not he’ll continue costume designing, Posen told the publication, “This wasn’t a glamour film. This was about texture, dimension, gangsters, and tailoring. And that was something very different for me. But it was about storytelling and character, which are things I love. I would definitely be interested in doing a fantasy film or an animated film. I obviously love theater, so working on a musical would be interesting. I just made these costumes for my partner Harrison [Ball] who did a choreography program for New York City Ballet, and that was really cool—to see clothing and movement in a different way.”