 The most recent novel in the series (book 5), "The Three Secret Cities", was released in Australia on October 30, 2018.Around 4,500 years ago, the capstone upon the summit of the Great Pyramid of Giza absorbed the energy released by the Tartarus Rotation (a monstrous sunspot that occurs every 4,000–4,500 years), and saved the earth from major flooding and catastrophic weather.This capstone was later divided up by Alexander the Great with one piece hidden in a booby-trapped location within each of the other seven wonders of the world.