Alison (Katherine Heigl), an anchor for the E! Network, receives a promotion, but the last thing she expects is for her celebratory night out to end in a pregnancy! Unemployed loser Ben (Seth Rogen), her one-night stand, is surprised to learn several weeks later that Alison is pregnant. Despite hardly knowing one another, and serious differences in personality and interests, they decide to make an attempt at making the relationship work, for the sake of the child. They face many challenges along the way; Alison becomes discouraged by her sister Debbie’s (Leslie Mann) marital troubles with her husband Pete (Paul Rudd). Ben hardly seems to understand the gravity of the situation, continuing his stoner ways and shirking responsibility left and right. Will they be able to make it work?