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On the first Sunday afternoon of May, an actual tumble-weed rolls down Thirty-fifth Street near Seventh Avenue in Manhattan. Eleven stories above that eerie, atypical scene, though, Jason Wu’s studio is bustling with photographers, stylists, a makeup artist, assistants, tailors, a Vogue writer, several custom floor-length creations, and one future movie star being fitted for her first Met gala appearance, just over 24 hours away.

Having recently wrapped the starring role in Sam Taylor-Johnson’s adaptation of Fifty Shades of Grey, Dakota Johnson, 24, stands poised on the precipice of fame – a position perhaps best comparable to Kristen Stewart’s on the verge of the release of Twilight.

“We’re presenting her to the world in so many ways,” says Wu, a designer who, having dressed Michelle Obama for the 2009 inauguration, knows a thing or two about first impressions. “She’s a little more shy than I expected – and she’s at the very beginning of forming her style. It’s something we’re working on together.”

And what better setting for a debutante moment than a white-tie ball? Still, it’s no simple trick to design a dress equally ap-propriate for both a Charles James-inspired affair and the elfin ingenue who wears it. As Wu puts it, “How do you do Charles James from the point of view of my generation, which is also Dakota’s generation?” The answer is a ball gown in separates: a navy-blue micro-beaded camisole tucked into a matching silk-gauze skirt with a Jamesian effect enhanced by layers of horsehair inserts underneath.

Finishing touches include black opera gloves fastened by pearls along the wrists (“So sexy and sneaky,” Johnson says), a mirrored Lee Savage clutch, Jennifer Meyer stud earrings, Lancome makeup, and Christian Louboutin heels hidden underneath it all. Though the once and future Anastasia Steele has many more red-carpet moments ahead, for now she simply takes one last look in the mirror.

“It’s nice to know that I’m wearing something I belong in,” she says.