Dragon Storm #6: Erin and Rockhammer

"When Erin and her dragon, Rockhammer, get into a fight with another dragonster they are sent away to a place called Stillness. There, Erin discovers a magical stone that helps her keep calm. But when dangerous soldiers storm Stillness, Erin will need to summon both Rockhammer and her courage to protect the things she loves most, or she will risk losing them forever..."--