Fighting Chance: Sometimes Horses Need a Little Magic (Horse Guardian, Band 11)

Chance and her best friend, Hanna, just want a fun, relaxing ride for their first excursion with the very young and super adorable Tubby, Chance's mare's foal, in tow. They don't want to tire or overwhelm him in any way.
When they happen upon their mean school rivals, the ride instantly becomes much less pleasant.
But even that pales in comparison to what is to come. Hanna and Chance are separated, a tornado descends from the stormy sky to wreak havoc, Tubby disappears, and then, unbelievably, everything becomes even worse!