tense thriller based on the novel by james siegel. charles schine (clive owen) and lucinda harris (jennifer aniston) have noticed each other on the commuter train before. one morning their conversation leads to a flirtation which turns into an evening of drink and then, before either one can stop it, a passionate one-night stand. but suddenly a stranger explodes into their world, threatening to expose their secret, and lures them into a terrifying game with more surprises than they saw coming and more danger than they may survive.