What a great read! It went so quickly for me and once I started it I didn't want to stop. 
 Rachel rides the train every day and sees the same couple in their backyard; eventually, she creates names and personas for them. But one day, she sees something in that backyard that changes everything. What she sees is not what you think and while the ending wasn't mind-blowing, it kept me wanting to pick up the book to know what happened next. In my book, that's pretty highly rated!