The girl on the train

Every day, Rachel takes the train... On her way to work, she always sees the same houses during her journey. In one of the houses, she always sees the same couple, to whom she assigns imaginary names and lives. In Rachel's eyes, the couple has a perfect life, almost identical to the one she recently lost.
Until one day...

Rachel witnesses something wrong with the couple... It's a quick glimpse, but enough to disturb her.

Unwilling to keep what she saw a secret, Rachel talks to the police. From then on, she becomes an integral part of a dizzying succession of events, affecting the lives of everyone involved.