Exclusive! How I Scored A Role In Karl Lagerfeld's Latest Film, <i>Once And Forever</i>

The call came early — 4 A.M., in fact. Out of the sensory blur came the tinkling French accent of a photo producer who works with Karl Lagerfeld and Chanel. "Karl is making a movie," she said. "And he would love you to be in it. Playing a journalist. You'd need to get on a flight to Paris tonight and go straight to set tomorrow morning. What do you think?"

Um, let me think about that, oui. Like I wouldn't. Like anyone wouldn't. Having had the privilege of relatively recent entry into Karl's orbit, I'd quite honestly fly to Paris to clean out his fridge and recycle his Diet Coke bottles.

Related article: Watch: A First Look At Kristen Stewart As Coco Chanel

But as anyone who is a fan of Chanel and the man behind it knows, the madly prolific Lagerfeld — in between producing eight annual Chanel collections (often shown in exotic, far-flung locales), five for Fendi, and his own collection; shooting Chanel and Fendi campaigns, magazine covers, and fashion sessions; sketching; painting; and generally being the smartest man in the room — also likes to make movies.

Well, short films. But short films with a grand story — the story of Chanel. "The idea is this," Lagerfeld explains about his latest, titled Once and Forever. "The final image of Chanel is not her youth, her lovers, her beauty — it's the old lady." While Chanel's life and lovers are storied (her most famed, Boy Capel, died tragically in a car accident in 1919), he is, of course, absolutely right. The popular vision of Coco is not her great beauty, her Deauville stripes; it's the old woman, in pearls and a hat. "It's a visual impact you cannot miss," he continues. "People who know the history of fashion know, but the public doesn't see the woman, who she really was. That's the story of the movie."

But this story is markedly more meta. It's a movie about a movie: Kristen Stewart plays an actress preparing for the role of the young Coco in a biopic. (Geraldine Chaplin plays the older Chanel in alternate scenes.) But something's gone awry — the film has lost its director, some untested French enfant has been hired, and Stewart, well, she's in a mood. "She's not the nicest person," Lagerfeld says of Stewart's role. "She is quite condescending. [Stewart's character mocks her costars and snubs the press.] It's a modern woman, the way some modern movie stars behave with the red carpet, the paparazzi, all of that. If I had made image after image of Chanel's past, it would be boring." He shrugs. "I wanted, for example, to shoot a costume test, the way it's done today."

A Chanel ambassador since 2013, Stewart has been photographed by Lagerfeld numerous times, but this was her first moving Chanel picture. "His interest in cinema is clear," she says. "Working with him in that way was inspiring — to see him in yet another shade of light." It also required improvisation. "I didn't have much of a chance to approach it until it was upon us, as we didn't receive scripts," Stewart recalls. "From the outside, it looked as though Karl was making it up as we went." She laughs. "And maybe he was."

My role is basically to follow Stewart (a lovely, cool, sensitive girl who I've known since Twilight was but a sunrise) around — in hallways, on movie sets — and be yelled at and have doors slammed in my face. It is awesome. Why me? I ask Karl. "Because you are full of life!" he replies. "And maybe you've been in this situation." (Like when I was 22 and chasing Sylvester Stallone up a Hard Rock Cafe red carpet — those heady days.) "Also," he adds, "I like to make movies with only people I like."

On set, however, Stewart's character couldn't like me less. I tell her to conjure up every bit of rage she's ever felt against the media, and she nearly blows me off the soundstage. It's so much fun being a pariah!

As with any film — and especially a Lagerfeld production — we spend a lot of time waiting. But what a crew to wait with. Karl's constant collaborators: Eric Pfrunder, Amanda Harlech, hairstylist Sam McKnight, and makeup artist Tom Pecheux. Karl's handsome cohorts: Sébastien Jondeau, Baptiste Giabiconi, and Jake Davies. Also, model Jamie Bochert, who I didn't know was in the movie until I found her in the next dressing room. (Ah, spontaneity.)

This is a gang at the top of its game, and also one that drinks wine at lunch. I never want to leave.

But like all good stories, this too has to end. Lagerfeld has gotten such a kick out of this one — his energy is infectieux. "I wanted it to be modern," he says. "And to give some humor to it. If not, it would be totally humourless."

He takes off his glasses and fixes me with a look. "Which the French love, but not me."

This article originally appeared in the December/January 2015 issue of Harper's BAZAAR US.