Children of the Lamp #1: The Akhenaten Adventure

When their wisdom teeth appear, twelve-year-old twins John and Philippa Gaunt develop extraordinary magical gifts, so they travel to London to meet their wildly eccentric djinn-uncle, Nimrod, who after teaching them to harness their new power sends them to find Akhenaten, a long-dead pharaoh, and his tomb, in hopes of rescuing seventy lost djinn trapped there, but they are soon engaged in a battle with Iblis, the most wicked djinn of all.