It was a simple promise—watch out for my best friend’s little sister the same way I would my own. Turns out, Brenna is a lot more grown-up than I realized. And a lot more beautiful. Which makes sharing an apartment with her this summer tougher than I expected. Until she shares something with me. Something she’s never shared with anyone. Something that makes me want to step in and help. Something that changes everything. Soon enough, my wanting to be with her has nothing to do with that promise I made and everything to do with the undeniable spark between us. It doesn’t matter that I’m more than a decade older than she is. Or what our small town thinks. But Brenna's time in Hickory Hills is limited, making everything more complicated. The more time I spend with Brenna, the harder it is to stay apart. The more I want to convince her to stay. I already broke my promise to her brother. But I will keep my promise to her. Even if I break my own heart in the process.