Tales of the Frog Princess, book 5: The Salamander Spell
E.D. Baker2007

In this prequel to the Tales of the Frog Princess, Grassina is a young princess-in-training. But as the younger sister to Princess Chartreuse, Grassina is not expected to do much beyond behave herself. When a terrible spell stops her mother from being the good Green Witch, and the Kingdom of Greater Greensward seems to teeter on the brink of terror, Grassina sets off on an errand in the swamp and comes back with some surprises for everyone, including skills that only Chartreuse is supposed to have. Soon it is clear that Grassina has begun to find her own way to the magic she thinks she'll never have, and luckily for Greater Greensward, the audaciousness—and the ability—to save the kingdom itself.

Titre original : Tales of the Frog Princess, book 5: The Salamander Spell (2007)