"Rosie and Jess have always been the greatest of friends, but more recently they've found themselves drifting apart. On the Autumn Treasure Hunt Ride, Rosie sets out to make amends. But what she discovers that day takes her down a path of deception and danger ..."

This is eight-year-old Carly's first summer at Storm Cliff Stables horse camp, and she is already having a hard time following all the rules, so when she finds a garter snake and decides to keep it as a pet, she needs to keep it a secret.

First year camper Kianna Drake is technically too young to be a Pony Girl at Storm Cliff Stables, but in two days she will be officially eight and she is feeling homesick and a little left out, because the other Pony Girls do not seem to care.

In her first year at Storm Cliff Stables horse camp Daniela Cruz is having a hard time fitting in, partly because her cousin Gabriela seems to be so much better at everything to do with riding than she is--but Dani is a superior swimmer, a talent that could save the day if she can find the special ring that Aunt Jane lost in the lake.

Bree has decided to give up riding after a bad fall at home, but she still enjoys summers at Storm Cliff Stables with her close friends, and learning how to care for the horses and other animals--but when the animals start disappearing one by one Bree is determined to solve the mystery.