Emma (Natalie Portman) and Adam (Ashton Kutcher) are life-long friends who almost ruin everything by having sex one morning. In order to protect their friendship, they make a pact to keep their relationship strictly "no strings attached." "No strings" means no jealousy, no expectations, no fighting, no flowers, no baby voices. It means they can do whatever they want, whenever they want, in whatever public place they want, as long as they don't fall in love. The question becomes -- who's going to fall first? And can their friendship survive?