A #1 Globe and Mail and New York Times BestsellerNamed a Best Book of the Year by The New York Times - The Globe and Mail - NPR - Publishers Weekly - The Guardian - Toronto Star - Kirkus Reviews - USA Today A major motion picture starring Emily Blunt and Justin Theroux. The debut psychological thriller that will forever change the way you look at other people's lives, from the author of Into the Water and A Slow Fire Burning (coming August 2021)Rachel takes the same commuter train every morning and every night. Every day she rattles down the track, flashes past a stretch of cozy suburban homes, and stops at the signal that allows her to watch the same couple having breakfast on their deck. She's started to feel like she knows them; she calls them Jess and Jason. Their life--as she sees it--is perfect. Then Rachel sees something shocking as she's passing by on the train--it's only for a minute, but it's enough. And now everything's changed, and she can't keep it to herself. But the police don't know if they should trust her as a reliable source. Soon she's deeply entangled not only in the investigation, but also in the lives of everyone involved. Has she done more harm than good?