Out of all the movies she has done - "Sicario," "The Edge of Tomorrow," and "The Huntsman," among many others, British actress Emily Blunt considers "The Girl On the Train" as her most challenging role yet.

In the movie adaptation of Paula Hawkins' bestselling novel, Blunt portrays struggling alcoholic Rachel Watson who is suffering from the divorce of husband Tom. Even though she has already lost her job, Blunt's character still takes the train daily to pretend to her flatmate that she still has a job.

Rachel likes to pretend that the couple she sees out the window of her train commute live perfect lives, but after she witnesses a crime, she gets involved in their lives more than she bargained for.

Speaking to Deadline, Blunt said that she absolutely loved her role in the film because there's more to Rachel than meets the eye.

"For me it's more about the portrayal of very damaged women. I just love that it's about addiction and loneliness and voyeurism and what we think we see and don't see. I think it's very relatable," she said. "We've all ridden the train to work and wondered about the lives of the people on the train, and I think that people relate to that. I love that your heroine, your lead character is the most unreliable witness in the world because she's a drunk. And yet she's right, and nobody believes her."

Blunt said that there's no other role quite like it, and the internal struggle faced by the character is a wonderful challenge to portray.

"The idea of playing a part like that where you just feel like you're drowning is exciting. I've never played a blackout drunk before, so this is new to me now," she shared.

When asked how she embraces a new character for a film, Blunt answered: "You just sort of take on this other person that you are not similar to. I don't know how to describe it other than it's sort of an ultimate form of empathy."

Other stars of "The Girl On the Train" include "Mission: Impossible - Rogue Nation" actress Rebecca Ferguson, "The Equalizer" actress Haley Bennett, "The Leftovers" actor Justin Theroux, "Fast & Furious 6" actor Luke Evans, "Mom" actress Allison Janney, "Joy" Edgar Ramirez, "The Comeback" actress Lisa Kudrow, and "Nurse Jackie" actress Merritt Wever.

"The Girl On the Train" will be released in cinemas on October 7, 2016.