Blake Lively is going full Diane Keaton in her upcoming movie A Simple Favor. Which is to say, she’s largely wearing crisp, elegant menswear, but with some dandy twists. A white bow tie here, a silk pocket square there; it’s all very luxurious and makes us wonder why Lively doesn’t do the menswear thing more often.

In the film—brought to you by “the darker side of Paul Feig,” hooray!—Lively plays Emily, a mysterious woman who befriends mommy blogger Stephanie (Anna Kendrick) after their sons become friends. Per the trailer, released Friday, Emily is an enigma. She struts around in three-piece suits and perfectly tousled hair, never far from a neatly crafted martini. Stephanie is easily pulled into her web, but it isn’t long before she realizes Emily has some big, Gone Girl meets Big Little Lies meets Goop-sized issues in her life.

“She’s like a . . . beautiful ghost,” Emily’s husband, Sean (Henry Golding), warns. Imagine describing your significant other in such a way! One day, Emily takes Sean up on that description and just disappears. Stephanie, armed with her vlogging capabilities, decides to dig her heels in and search for her missing friend. Her detective work leads her to an ominous Bible camp, as well as a grouchy artist (played by Linda Cardellini), who warns that Emily’s past is terrifying: “I’ve never seen such a beautiful girl want to be so invisible,” she says. From there, the trailer is a montage of terror: there’s a car crash, a body being pulled out of the water, and Sean being taken away in handcuffs by the police. The dark side of Paul Feig indeed.

A Simple Favor hits theaters on September 14. If we’re lucky, Lively will do the entire press run in a series of bespoke, three-piece suits that would make even Keaton tremble.