• Emily Blunt and husband John Krasinski arrive for the formal Artist's Dinner in 2011.

Emily Blunt and husband John Krasinski arrive for the formal Artist's Dinner in 2011. (Photo : Getty Images/Ron Sachs-Pool)

The first official trailer of the upcoming "The Girl on the Train" debuted on April 20, Wednesday, with quick cuts, eerie voice-overs and a remix from Kanye West's 2008 "Heartless." The movie will be in cinemas on Oct. 7.

"The Girl on the Train" is inspired by Paula Hawkins' 2015 novel of the same title. British actress Emily Blunt, 33, plays a divorcee, Rachel Watson, who got involved in the mystery of her ex-husband's nanny Megan Hipwell (Haley Bennett), who disappeared and was murdered.

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Rachel went to the police to tell them what she thought she saw on the train but she became one of the suspects. She had been staring at the house of her ex-husband and his new wife from the train. That got her involved in the crime, even if she just gazed for curiosity.

Megan Hipwell, the unknown and complex woman, seemed to be in control of her life, compared to Rachel who is alcohol-dependent, according to Entertainment Weekly. Everyone, especially the handsome men, was a suspect. Both Rachel's ex-husband Tom (Justin Theroux) and Scott Hipwell (Luke Evans) have stares that make it difficult to tell who really the killer is.

A hand grabbed a female blonde's head, which could either belong to Rachel or Tom's new wife Anna (Rebecca Ferguson), and that is another mystery. The detective (Allison Janney) is not someone to mess with and she seemed to be not on Rachel's side.

The detective asked Rachel, "Did you murder Megan Hipwell?" in which she replied "No." However, there were times Rachel was not herself and she even told psychiatrist Kamal Abdic (Edgar Ramirez), "I'm afraid of myself."

Blunt was pregnant with her second child while filming the movie. She told Deadline that playing Rachel Watson was most challenging for her.

"I love that your heroine, your lead character is the most unreliable witness in the world because she's a drunk," Blunt told the publication. "And yet she's right, and nobody believes her."

Here is the first official trailer of the upcoming film, "The Girl on the Train."