Rachel takes the same commuter train every morning that allows her to daily watch the same couple breakfasting on their deck. She’s even started to feel like she knows them. And then she sees something shocking. It’s only a minute until the train moves on, but it’s enough. Now everything’s changed. Unable to keep it to herself, Rachel offers what she knows to the police, and becomes inextricably entwined in what happens next, as well as in the lives of everyone involved.