Vanity Fair – Comedy director Paul Feig turns dark with his latest film, A Simple Favor—a noir thriller starring Blake Lively, Anna Kendrick, and Crazy Rich Asians breakout Henry Golding—which gives its cast a chance to portray the sort of sinister characters they’ve never played before.

“It was so much fun to play someone who is so incredibly heightened. My character is a complete psychopath,” said Lively at the film’s premiere, held at the Museum of Modern Art in New York on Monday. “She’s so different than me. I don’t really swear, and I don’t drink. The whole experience was fun. I got to be a wild child.”

Lively, who arrived at the premiere with husband Ryan Reynolds, was thrilled to work with Feig on a genre-bending movie like this one. “He cranks these characters up, and makes them so over the top that it makes it comedic and funny,” she said. “I love that, because every day we had complete freedom to be emotional—to be over the top, funny, and to make bold choices. You don’t always get that. Sometimes you’re boxed in.”

Based on Darcey Bell’s popular 2017 novel, A Simple Favor (out September 14) centers on perky, type A, suburban-mommy vlogger Stephanie Smothers (Kendrick), who seeks to solve the sudden disappearance of her new friend, Emily Nelson (Lively). Emily vanishes after she asked Stephanie for a simple favor: to pick up her son from school one afternoon. Stephanie and Emily’s husband, Sean Townsend (Golding), set out to find where she has gone. The missing-person plot takes several warped twists and turns, keeping moviegoers off-balance as the mystery unfolds.

Golding, for one, said he was “gobsmacked” by that serpentine plot. “There are these moments where I was like, ‘This is insane!’ And there is a lot of potty-mouthed dialogue, and it comes from surprising areas.”

Kendrick, tasked with playing an overzealous parent who video-blogs about homemade gazpacho, also found the film demanding—especially when her character had to go up against Lively’s.

“O.K.—for real, it was a challenge,” the Oscar-nominated actress said on the carpet. “The character that I end up going head-to-head with is a very strong, beautiful woman, and my character is lonely, and she’s awkward, and doesn’t always say the right thing. So I tried to show her humanity as much as I could, because normally if I’m in a situation where I’m up against a 5-foot-10-inch blonde who’s beautiful, well dressed, and wealthy, I rely on wit and my sense of humor. And that wasn’t something that I could rely on with Stephanie. So I really had to dig deep and find the ways that I could show you that she’s been through trauma, and behaves in ways that are off-putting because she’s trying to cover the darkness that she feels inside of her. It was a lot of emotional work, but it was really fun. And it’s nice to have that kind of challenge.”

As Emily’s morally ambiguous husband, Golding upends expectations at every turn. It’s a role completely opposite from his lovable, swoon-inducing on-screen persona in Crazy Rich Asians.

“You’re kind of unsure if my character is good or bad,” said Golding. “That’s something that I want to continue—not just be stereotyped and be the heartthrob and romantic lead, but to play as diverse [of] characters as possible.”

Golding had finished Crazy Rich Asians, his first big-screen role, a mere two weeks before Feig contacted him about A Simple Favor. Feig had learned about Golding through his wife, a fan of the Crazy Rich Asians books who had been following news about the movie. “I watched all of Henry’s travel shows that he hosted, and I fell in love with him,” said Feig. “He’s so charming and so charismatic. And then I called Jon [M. Chu, who directed Crazy Rich Asians,] and asked, ‘Can he act?’ And he said, ‘He’s the best. He works so hard. He’s the nicest guy in the world.’ And I was like, ‘He’s in!’ Henry is a movie star that I have not seen in a long time. He’s a version of Cary Grant.”

Since the release of his first blockbuster, Golding’s life has changed dramatically. He’s getting recognized on the street, sitting in the front row at fashion shows, and enjoying the perks of fame—especially the special treatment he gets at airports.

“One time, I got picked up at L.A.X., and they have this special car that takes you from the plane on the tarmac directly to the other place where they collect your bags,” he revealed. “It was like a little strange look into the world of Crazy Rich Asians. I’m not used to that at all. That was a treat!”

Warning: Minor spoilers ahead. 

From crystal-studded Christian Louboutins to a snap-off dickie (yes, dickie), there is more than a concession stand’s worth of fashion eye candy in the dark comedic thriller A Simple Favor. But one accessory truly stole the spotlight: the giant sapphire-and-diamond engagement ring that Blake Lively’s character, Emily Nelson, wears, which once belonged to the character’s mother-in-law — and serves as an important plot point for the film.

The dazzling piece bears an uncanny resemblance to another (very famous) family heirloom, and according to the film’s costume designer, Renée Ehrlich Kalfus, that similarity was on purpose.

“It’s a take on Princess Diana’s ring,” she says, referencing the 12-carat oval sapphire surrounded by diamonds that’s now worn by Kate Middleton. “I wanted to do something vintage, but the director [Paul Feig] thought it should be more on the nose.”

The traditional ring is an interesting choice for the anything-but-traditional Emily. She’s a high-powered fashion publicist who works in New York City, but lives in a Connecticut suburb with her husband and son, much to her dissatisfaction. “She doesn’t care about fitting in,” Kalfus says of the character. “She had her own agenda.”

To convey that message, Kalfus looked to a trio of iconic Hollywood stars — Katherine Hepburn, Lauren Bacall, Diane Keaton — as well as the movie’s director for inspiration. “Paul goes to work every day in a Savile Row suit,” says Kalfus of Feig, who also directed Bridesmaids and Spy. “He feels he can get anyone to answer anything while wearing a suit.”

She then tapped Feig and Lively’s contacts at Ralph Lauren for access to their vintage archives and was able to use several looks, including a three-piece suit and a killer tuxedo, all custom-tailored for Lively. Kalfus decked out each look with men’s jewelry like vintage watch fobs and multiple tie bars. “It gave her more armor, more stuff to keep people away,” says Kalfus.

Even covered up head-to-toe in a suit, Emily finds ways to flash more than just a little skin. In one early scene, she removes her jacket and shirt (which turns out to be not much more than a collar), before enjoying a gin martini (her signature drink) in a low-cut vest and a pair of faux cuffs, while her new (and visibly flustered) mom friend, Stephanie (Anna Kendrick) looks on.

“I don’t think we told Anna that it was going to happen,” says Kalfus of the striptease-like sequence. “It was just a way of making Emily more intimidating and kind of weird.”

In a later scene, Emily appears to forgo a top altogether under her suit jacket, although Kalfus swears she had on a blouse. (“It was very strategically tucked into a cummerbund, just enough to give a little side boob.”)