Will and Rosie meet as teenagers. They're opposites in every way. She overthinks everything; he is her twin brother's wild and unpredictable friend. But over secret walks home and late-night phone calls, they become closer - destined to be one another's great love story. Until, one day, tragedy strikes, and their future together is shattered. But as the years roll on, Will and Rosie can't help but find their way back to each other. Time and again, they come close to rekindling what might have been. What do you do when the one person you should forget is the one you just can't let go?