The Bartimaeus Sequence Set

Nathaniel is a young magician's apprentice, taking his first lessons in the arts of magic. But after a devious hotshot wizard named Simon Lovelace ruthlessly humiliates him in front of everyone he knows, Nathaniel seeks his revenge through magic. He pores over texts and works to perfect his skills to summon the 5,000 year old djinni Bartimaeus-but Nathaniel may have bitten off more than he can chew, and soon finds himself in a situation more dangerous and deadly than he could have ever imagined.