Clara Thorn, the witch that was found

Poor Clara. On the one hand, things are going well: she’s aced her Math final, and school’s almost out for the year. Dad’s hanging in there with contract jobs, Mom’s helping make ends meet by cleaning other people’s homes, and they’ve at least got a roof over their heads. Vegas isn’t the nicest place in the summer, but it’s no worse than the half-dozen other places she’s lived in her short life.
But on the other hand, she has no friends. Everyone at school is either diffident or a bully—as if they can sense that Clara doesn’t quite fit in. And then there are the triplets, who mysteriously vanish in the Art Alley near the school.
That’s when things get interesting.
Clara follows them through a Border to Underhill, and before long she’s thrown into a world she never knew existed. A world of magic, witches, excitement, and danger. It seems she’s apparently the only one who can save all of Underhill from an exile who wants to trap them all and cut off the source of magic!
Also, she’s pretty sure her parents knew about this all along.