I really wanted Rachel [from the Girl on The Train] to be purely fixated on fantasy and on her ex-husband.I didn't want her to be embarking on romance, touching people I wanted her purely in the realm of fantasy and frustration and dreaming and sadness.

It's what you do when you have Allison Janney.My jaw-dropped at her performance. You think that part is sort of a regular part until she steps into the shoes of the officer. She just filled it with such dimension and by giving her the whole shebang, the whole police thread, I think it was the right choice.

The gaslight of the film [The Girl On The Train] became something that really needed to be dramatized more than the book did, because it wasn't going to read as strongly on screen.

Just because Rachel [from the Girl On The Train] is an unreliable character doesn't mean she has sex with anybody who walks by her. It was important to keep her a little virginal.