"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."

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I needed to enhance the outward threat to Rachel.In the book [Girl on the Train], her inner threat is so strong; the fear of herself and her inability to remember and the false memories. In the film [Girl on the Train]I wanted to increase the exterior threat. So that's why Allison's part was bigger and was an important part of the climax of the film.

— Erin Cressida Wilson