The book-to-film adaptation of The Girl on the Train has found its final co-lead in Haley Bennett.

The actress will be playing Megan, the person who Rachel obsessively observes from “the train” every morning until the former goes missing. The sudden disappearance causes Rachel to take the investigation into her own hands because her unstable frame of mind leaves her desperate for answers.

Haley Bennett is known for roles in last year’s The Equalizer and 2008’s Marley and Me. The actress rounds out a trio of stars who will take on the lead roles in the film directed by Tate Taylor — Emily Blunt will play Rachel while Rebecca Ferguson will portray Anna.

“Rachel takes the same commuter train every morning. Every day she rattles down the track, flashes past a stretch of cozy suburban homes, and stops at the signal that allows her to daily watch the same couple breakfasting on their deck,” reads the book’s synopsis. “She’s even started to feel like she knows them. ‘Jess and Jason,’ she calls them. Their life — as she sees it — is perfect. Not unlike the life she recently lost.

“And then she sees something shocking. It’s only a minute until the train moves on, but it’s enough. Now everything’s changed. Unable to keep it to herself, Rachel offers what she knows to the police, and becomes inextricably entwined in what happens next, as well as in the lives of everyone involved. Has she done more harm than good?”

The Girl on the Train is expected to open in theaters next year and arrives on the heels of a successful summer for Paula Hawkins’ latest novel. The thriller has been compared to Gone Girl thanks to its surprising twists and compelling characters.

Needless to say, we can’t wait to see it in theaters in 2016.