A British import reminds us that there are historical potboilers for the young even as there are for their parents in this overblown and under-plotted first of a trilogy. From 1185 to 1193, readers follow hot-blooded and hard-hearted Gavin, his younger brother William, bright and compassionate, and their father’s ward Eleanor. Thomas de Granville, the boys’ father, goes on Crusade with King Richard Lionheart; his sons go with him and Eleanor stays behind to learn to read and fend off a slimy suitor. The most vivid character is Hosanna, the red horse of the title, a fierce, intelligent, graceful animal who carries William to Jerusalem and back during the Crusaders’ battles with the leader Saladin (a historical trope handled far more compellingly by Catherine Jinks in Pagan’s Crusade, 2003). The human characters have little depth or energy—21st-century cardboard cutouts set in a medieval frame. On the other hand, it is a page-turner, as Hosanna overcomes mistreatment, attack and injury to inspire both William and Saladin’s assistant Kamil, into whose hands the horse briefly falls. (Historical fiction. 10+)