迈克(萨姆·沃辛顿 Sam Worthington 饰)和乔安娜(凯拉·耐特丽 Keira Knightley 饰)是一对令人羡慕的年轻夫妻,迈克拥有安稳工作、乔安娜是自由作家,二人居于曼克顿的时尚住宅,生活无忧。两人出席迈克的工作派时,乔安娜发现新来的女同事罗拉(伊娃·门德斯 Eva Mendes 饰)对丈夫态度暧昧,心情不佳,而迈克对妻子反应亦不以为然。没过多久,迈克和罗拉一起去外地出差,同时心神不安的乔安娜则在曼哈顿街头巧遇了曾经深爱过的旧情人艾力克斯(吉约姆·卡内 Guillaume Canet 饰)。 在这一夜,迈克能够抵抗住美丽罗拉诱惑?乔安娜又会不会和艾力克斯旧情复燃?精神外遇或肉体外遇,哪一种出轨方式对婚姻杀伤力最大?这一对伴侣是否可以回到原来平静的生活?Joanna accuses her husband, Michael, of being attracted to his co-worker. Wanting to make-up before he goes on a business trip, she assumes she over-reacted. But when they are both away from each other for one night, Michael ends up testing his loyalty to Joanna and his attraction to Laura. And Joanna tests her honesty to Michael when her ex-boyfriend Alex suddenly appears in New York for the day.