What If is the story of medical school dropout Wallace (Daniel Radcliffe), who's been repeatedly burned by bad relationships. So while everyone around him, including his roommate Allan (Adam Driver) seems to be finding the perfect partner (Mackenzie Davis), Wallace decides to put his love life on hold. It is then that he meets Chantry (Zoe Kazan) an animator who lives with her longtime boyfriend Ben (Rafe Spall). Wallace and Chantry form an instant connection, striking up a close friendship. Still, there is no denying the chemistry between them, leading the pair to wonder, what if the love of your life is actually your best friend?