Brooke Rhodes is excited to go to sleepaway riding camp for two weeks with her Chincoteague pony, Foxy. However, camp doesn't turn out to be quite as fun as Brooke expected. The other girls all know each other already, and they don't seem interested in bringing a newbie into their group. Besides that, they're all riding tall, fancy, super well-trained show horses--not scruffy young Chincoteague ponies. Then Brooke overhears that this might be the last summer for the camp. She asks for help from her online Pony Post friends--Maddie Martinez, Hayley Duncan, and Nina Peralt--but she still has to wonder: will everyone work together to save the camp, or will this summer be their last hurrah?