A new trailer has been released for this fall’s highly anticipated “The Girl on the Train.” In it, we hear more from Rachel Watson, the unreliable narrator who has galvanized readers since Paula Hawkins’ best-selling book “The Girl on the Train” was released in 2015. The suspenseful, sordid tale was hailed as “the next ‘Gone Girl’” when it was published, and the film adaptation is earning similar comparisons.

Emily Blunt (“Sicario”) takes on the role of Rachel, an alcoholic woman whose life is in shambles. “I used to watch this perfect couple,” Rachel recalls in the trailer. “They were the embodiment of true love.” But then one half up the couple goes missing and Rachel becomes fixated on the disappearance of the woman, Megan (Hayley Bennett, “The Equalizer”), who Rachel’s ex (Justin Theroux, “The Leftovers”) employed as a nanny. It’s not long before Rachel becomes a suspect in the crime.

Rachel has witnessed something in a tunnel that she cannot forget — but she can’t quite remember it either. She holds the keys to the mystery but her lapses in memory make it impossible for her to make sense of what’s happened.

And the “perfect” couple may not be as perfect as they appear from afar: Megan say she “wants to start [her] life over again” in the clip, suggesting that she’s in need of a fresh start. Plus, the new trailer makes it seem as though Megan’s therapist may have some boundary issues.

There are a lot of loose threads for anyone to connect — never mind someone struggling with addiction like Rachel is. But she’s committed to uncovering the truth.

Blunt has said that playing Rachel was “the most challenging thing [she’s] ever done.” The role certainly looks intense — particularly the scene where Rachel tearfully confesses to who she’s most afraid of.

Check out the gripping trailer below. “The Girl on the Train” opens October 7. The script was penned by Erin Cressida Wilson (“Men, Women & Children”).