Fashion folk have a thing for Tilda Swinton, and finally Swinton is in a fashion-driven film.

“Io sono l’amore” (“I Am Love”), due in theaters this spring, is coproduced by Silvia Venturini Fendi and stars Swinton as a well-heeled woman of Russian descent who marries into a wealthy and powerful Italian clan. (This being Swinton, everything is not as it seems. Her character ends up in a steamy affair that has tragic repercussions for the family.) Costume designer Maria A. Cannarozzi dressed Swinton exclusively in Jil Sander dresses, suits and coats in rich hues to help set the tone. “This is a woman who marries into a very particular milieu, a very strict world, and she needs a uniform,” said Swinton after showing the film at Soho House on Friday to an audience including Bruce Weber, Tony Gilroy, Justin Bond, Italo Zucchelli, Allison Sarofim, Jim Jarmusch and Waris Ahluwalia.

Swinton continued, “Her mood is indicated by colors, but her silhouette is always slightly hidden. You never really know what shape she is or what real body she has until she takes her clothes off.”

The actress was equally enthusiastic about the frock she donned for the screening — a short black number with zippers on the hems and sleeves — but not as well versed. “That’s a really good question,” she said when asked who designed it. “It’s by some unnamed, rad English designer who sent it to me. I don’t know.” But the coat she wore over it was Jil Sander.