Jinn Hunter: Book Two - The Jinnslayer. Jinn Hunter, #2

Oddball and loner Oliver Quinn was raised by his uncle, the proprietor of Ozymandias & Son, New York's most bizarre emporium of Oriental rugs. Through a series of what he believes to be coincidences, Oliver discovers a portal in the basement of the shop - a portal to a magical world called Zonus. Gradually, Oliver begins to understand that everything he'd ever considered fact is fantasy, and that if he is to survive, he'll have to start thinking in an entirely new way. In reality, our world is nothing but a backwater in a colossal multiverse, where every permutation is not only possible, but certain.
With the veil lifted, Oliver is introduced to the parallel life form with which we share the multiverse - the mysterious and all-powerful race of jinn. Far from the loveable blue-skinned giants projected by Hollywood, jinn are capable of wreaking terror on an unknown scale. When they go rogue, as they frequently do, they must be captured and incarcerated in the Prism, a vast penitentiary. Trapping rogue jinn is a perilous task entrusted to the Jinn Hunters, the bravest fraternity of warriors in existence. Having been accepted into the Cadenta, the training academy of Jinn Hunters, Oliver is pitted against the gravest new reality: the fact that Nequissimus, the most evil jinn in all existence, has just escaped... Born into the hallowed ancestry of the Jinnslayers, Oliver Quinn is the only man alive with a chance at defeating the great jinn, and returning him to his cell in the Prism. A cross between A Thousand and One Nights and Men in Black, THE JINNSLAYER is the second awe-inspiring novel in Tahir Shah's much-celebrated JINN HUNTER series. One of the most original books of its age, it lures the reader into a twilight zone conjured from pure imagination.