Lou Clark knows a lot of things. She knows how many steps it takes to walk from the bus stop to her parents' house. She knows she enjoys her job and that she's probably not really in love with her boyfriend, Patrick. What she doesn't know is that she will soon lose her job. She also doesn't know that everything she thought she knew, which made her feel balanced and rational, is about to be overturned and changed forever.

Will Traynor knows very well that the motorcycle accident that left him paralyzed has stripped him of any passion for life. He also knows that everything seems indifferent to him and he knows exactly how he will put an end to this unbearable farce. What he doesn't know is that Lou will burst into his life like an explosion of color and light. He doesn't know that, unwittingly, this strange woman will break down his defenses.

Ultimately, neither of them can imagine how deep the change they will cause in each other will be, how indelibly their meeting, their acquaintance, their love will mark each other's existence.