The Moonstone

In a world where elemental magic rules reality, every person has a spirit that allows them to wield elemental magic. Rose grew up believing that she had no magical abilities. However, one day she burns a boy with fire magic. It turns out that she can wield fire... and this is only the beginning of the mysteries she will have to face.
By chance, she discovers a country hidden from the rest of the world, where she learns that her life so far has not been so simple and safe. Rose must hide from a magician who seems to want something her brother has-the spirit of a long-dead king, whose existence is the key to the ancient elemental spirits.