The Sorcerer's Apprentice.

Valentin, a destitute vagabond, seeks his fortune in the rat-infested city. It just so happens that Master Argus, the great wizard of the land and advisor to the queen, is in need of an apprentice. Valentin is sure that magic is just the thing for him. Although his amazing talent is revealed during the test, he is tricked by Katrina, the only competitor, and doesn't get the job. Instead, he finds shelter in the pharmacy of old master Zacharias. However, due to a terrible accident of his own making, he no longer works magic and for the time being only teaches Valentin the secrets of herbalism and medicine. Deeply dissatisfied with this, Valentin sets about learning the art of magic on his own. Beginning with the plague of rats that has appeared and disappeared overnight, he discovers a series of secrets that are all miraculously interlinked.