The Golem´s Eye (The Bartimaeus Trilogy 2)

Nathaniel and the devious djinn Bartimaeus are back, bickering as always, in a follow-up that rivals the first book in intensity and action. When we meet up with Nathaniel, he's 14 now, apprenticed to Jessica Whitwell, and the government's current "it boy." His growing reputation as someone who can get things done lands him the responsibility of dealing with the resistance movement's incessant raids. But when his progress in the investigation is hampered and with his standing in the government at stake, Nathaniel is forced to seek additional assistance.

Enter Bartimaeus, Nathaniel's reluctant (and often belligerent) servant. They're not far into their joint investigation when a series of horrible attacks --- committed by a Golem controlled by an unknown wizard --- sends them on a new course. They soon find themselves in Prague in a desperate attempt to uncover the true menace behind the attacks.