Samantha's friend Ryan wants to capture his horse Hotspot, who has been running with the Phantom Stallion's herd.

A movie star horse and his trainer come to River Bend Ranch.

At her grandfathers horse ranch on Hawaii, Darby Carter tries to win the trust of the mustang which she had rescued.

When a volcano erupts and leaves Darby and Hoku stranded during a camping trip, Darby must think quickly to save them both and prevent the untrained mustang from returning to the wild.

Sam meets Nicholas, a boy traveling on a Gypsy Vanner mare that looks like a missing mustang. Sam wants to stick up for Nicholas but should she really trust this new friend?

"When an earthquake sets off a tsunami on the shores of Wild Horse Island, the mustangs of Crimson Vale are chased by the waves and left stranded on a dangerous hilltop. Darby knows the lead mare, Medusa, will do anything to save her herd. But will she let the ranch hands bring her to safety?, or is it up to Darby to save Medusa and her band before they're lost forever?"--Cover, p. [4].