A young slums girl who accidentally finds out she has magical powers that are developing. This being extremely dangerous - the magical power could blow like a bomb if not controlled - and is chased by the Magicians of her city. They need to teach her to harness her power. It tells of her apprentceship and of the life in the slums with the Thieves. But she has to use he powers to defend herself when the High lord and herself are banished. I loved these books (and am reading them again now) and highly recommend them to everybody. A new book that is a prequel to these came out last year, explaining how the magicians guild came to be.