Gift Horse — Dandi Daley Mackall

I almost wished Summer's little crowd would have laughed at her snotty words. That they didn't, that they maybe felt sorry for me, was worse. Was I someone you feel sorry for?

Just when Winnie Willis feels like school could be almost tolerable, Summer Spidell has to be ... well, Summer. Worse, Winnie's friend Hawk is away for Christmas vacation, and Winnie is lonely. Then a mysterious horse shows up in the pasture behind her house. Suddenly Winnie is caught in a life-and-death struggle with the old mare.
Who is the horse's owner? Will Winnie be able to keep -- and save -- this "gift horse"?