Rachel spends most of her days watching this couple she calls Jason and Jess. She doesn’t know their real names she just one day noticed them on her train ride. She has had a tough few years. Her and her husband Tom were trying for a child but were unable to later she found out he was cheating online with someone she'd never heard of. Their marriage ended she moved out and started drinking. Scott now lives with Abby and their child and Rachel’s alone. So to get through her days she watches Jess and Jason.

Rachel doesn’t have many friends and she lives with her roommate Cathy, a friend from college. She doesn’t mind living with her, but she does feel like a guest who’s overstayed their welcome. She wakes up every morning pretending she still has a job; however she doesn’t and if Cathy would ever find out Rachel would be homeless. So she rides the same train, watching the same couple, living the same lie everyday.

Rachel is upset that she hasn’t seen Jess in a few days and that the last time she saw her she was kissing someone. She confronts Jason to see what happened and learns his name is Scott and his wife’s name is Morgan and that she’s missing. He doesn’t know if she was murdered or just kidnapped or what the motive even was.
All the characters seem like liars at one point or another and at points in the book I wished I could’ve told her who not to trust. There’s secret relationships between people and I wondered of that could be a big enough of motive for murder. This book filled me with suspense, making me wonder if I was already introduced to the guilty suspect,and if certain accusations I made against certain characters were right.