Who said mistakes have to be bad? It's Christmas break and I'm alone. My best friend is off with the dance team to the Bahamas and I'm at home, trying to pad my college application by volunteering with Safety Net Mentors, a program that pairs teens with kids in need-and if I finally get to talk to my lifelong crush, I'm okay with that. Everything is going according to plan until I discover that not only is my ex-best friend, Grayson back, but he's also volunteering. And we get paired with siblings. Great. I not only have to talk to him but I have to spend time with him and his mentee. Which seems doable as long as neither of us bring up the past. Which seems harder to do than say. Now I'm so confused, I can't keep my mind straight. There's something Grayson isn't telling me and feelings that creep up that weren't there before. Things change and suddenly, what felt like the biggest Christmas break mistake doesn't feel that way anymore. If only I could figure out what everything meant, I just might survive with my heart intact. For fans of Young Adult romance, Rule #10: You Can't Forgive your Ex-Best Friend will suck you in and not let you go until the very end.