It's Christmas time in the outback and the Sunhaven teens are determined to have a quiet time after their past adventures - no plans, no excitement, no life-threatening thrills, just the usual Christmas-time activities. The peace is broken by the brewing storms, and as hot days end with lightning in the distance, they know the floods are on their way. There are personal storms, too, as Dane struggles with depression while his family and friends try to help, and Amy is desperate to discover if her father is still alive. When the record-breaking rains arrive, their part of the outback becomes an inland sea, and a neighbor's horses and cattle are doomed to drown unless the outback riders saddle up and risk their lives to save them.

Horses of the Rain is the fourth in The Outback Riders series, and the teens are a bit older and facing problems that many teens need to overcome. They are falling in love, making plans for the future, and finding their way through life. Polo, the rock star, returns to ride with them, and the Min Min lights continue to watch over them.