His sister (a Niall story)

Cassie lived with her mom in the bad part of new York. Drugs and sex is all she's around, because of her mom. One bad thing happens and leads her in one direction. She has a father, that she didn't know about. She is forced to live with him, after a tragic event. But she also had a bother? And what happens when she falls for his best friend? A very protective Liam, is what you get!