It tells the story of a working mom who meets a stranger who upends her life. She questions whether we can ever truly know the people closest to us.

Selena Murphy is commuting home on the train when she strikes up a conversation with a beautiful stranger in the next seat. The woman introduces herself as Martha and soon confesses that she's been stuck in an affair with her boss. Selena, in turn, confesses that she suspects her husband is sleeping with the nanny. When the train arrives at Selena's station, the two women part ways, presumably never to meet again.