Sisters are off limits to best friends right? What happens when you just can't help it? Niall's been looking for his princess for a long time now and he's started to think that maybe he doesn't have one and is destined to be forever alone. Except, when you're a world famous pop star that's not really allowed. Rhyleigh Payne was just the little sister Liam Payne had left behind to follow his dreams. Bullied, alone and missing the person she was closest to, she's unsure of what she's doing in her life. To her, love is just something that's way out of her league, something that she doesn't deserve. But could a certain Irish lad change that definition? When a sister falls in love with a best friend will the true love be forbidden?