A hurricane hits the islands of Asseteague and Chincoteague just as Misty (the mare featured in the first of Marguerite Henry's horse lover's book series Misty of Chincoteague) is about to give birth to her foal. In this story of survival and hope the wild horses of the islands along with the people that live there must overcome the challenges brought on by the terrible damage and flooding that was caused by the storm.