Charmseekers: The Silver Pool by Georgie Adams (author)

At their first riding lesson Sesame and Maddy are watching Silver being re-shod, when they’re whisked back to Karisma to hunt for another magical charm. But they’re up against Zorgan the sorcerer and his wicked pixie puppets, Nix and Dina. Treacherous Zorgan has raised the spirit of the dragon Agapogo who guards the fabled silver pool. Now the pool has dried up, there’s no more silver and the Silversmith and Queen Charm are in despair. And when there are charms to find evil Morbrecia, the queen’s older sister, and her gribblers are on the trail. The race is on to find the charms which will restore order and harmony to the kingdom.