Mairelon the Magician — Patricia C. Wrede

Kim doesn't hesitate when a stranger offers her a small fortune to break into the travelling magician's wagon in search of a silver bowl. Kim isn't above a bit of breaking-and-entering. Having grown up a waif in the dirty streets of London-disguised as a boy!-has schooled her in one hard lesson: steal from them before they steal from you. But there is something odd about this magician. He isn't like the other hucksters and swindlers that Kim is used to. When he catches her in the act, Kim thinks she's done for. Until he suggests she become his apprentice. Kim wonders how tough it could be faking a bit of hocus pocus. But Mairelon isn't an act. His magic is real.