Jessica Burkhart 
Take the Reins [EPUB ebook] 

When Sasha Silver and her horse, Charm, arrive on the campus of the elite Canterwood Crest Academy, Sasha knows that she’s in trouble. She’s not exactly welcomed with open arms. One group of girls in particular is used to being the best, the brightest, and the prettiest on the team, and when Sasha shows her skills in the arena, the girls’ claws come out. Sasha is determined to prove that she belongs at Canterwood. Will she rise to the occasion and make the advanced riding team by the end of her first semester? Or will the pressure send Sasha packing?