May 2 (UPI) -- Blake Lively goes missing in the first teaser trailer for A Simple Favor.
The preview follows Stephanie Ward (Anna Kendrick), a blogger who investigates the mysterious disappearance of her best friend, Emily Nelson (Lively), from their small town.
Stephanie considers Emily as a "wonderful, elegant person," although Emily's husband (Henry Golding) describes his wife as an "enigma." Stephanie soon learns her friend may have had a secret life.
"Everybody has a dark side. Some of us are better at hiding it than others," she says in the clip.
Lively promoted the movie this week by deleting all of her Instagram photos and adding the biography, "What happened to Emily Nelson?"
A Simple Favor is based on the Darcey Bell novel of the same name. Paul Feig (Bridesmaids, Ghostbusters) directed the film, which co-stars Joshua Satine, Linda Cardellini, Eric Johnson and Jean Smart.
"I've always been looking for a kind of Hitchcockian-style thriller. This one provided that," Feig told Hollywood Streams in April. "Lots of great twists and turns, but also two very fun, compelling characters."
A Simple Favor opens in theaters Sept. 14.