From Amazon, here's the synopsis:
Despite her father’s warnings that their tribe is always in danger, Casita, a ten-year-old Lipan Apache girl, has led a relatively peaceful life with her tribe in Mexico, doing her daily chores and practicing for her upcoming Changing Woman ceremony, in which she will officially become a woman of the tribe. But the peace is shattered when the U.S. Cavalry invades and brutally slaughters her people. Casita and her younger brother survive the attack, but are taken captive and sent to the Carlisle Indian School, a Pennsylvania boarding school that specializes in assimilating Native Americans into white American culture. Casita grieves for her lost family as she struggles to find a way to maintain her identity as a Lipan Apache and survive at the school. Includes author’s note and bibliography.
From what I can tell, this is the third volume in the Hidden Histories series from Boyds Mills. The series is "spotlighting little-known tales from America's past, and the children behind those stories."
I hope that MacColl and her editor studied the problems in Ann Rinaldi's book, My Heart is on the Ground, also set at Carlisle, and that they aren't repeating errors Rinaldi made. If/when I get the book, I'll be back!