World of Jinn: Ptolemy’s Gate by Jonathan Stroud

Three years have passed since the magician Nathaniel helped prevent a cataclysmic attack on London. Now an established member of the British Government, he faces unprecedented problems: foreign wars are going badly; Britain’s enemies are mounting attacks close to London; and rebellion is fomentingamong the commoners. Increasingly imperious and distracted, Nathaniel is treating Bartimaeus worse than ever. The longsuffering djinni is growing weak and vulnerable from too much time in this world...