A missing explorer, mysterious stone formations, a sign in the sky - geologist Ella Jordan is faced with a mystery. As she ventures down to the lowest point on Earth, the events seem to make a terrible sense. From the Mariana Trench, signals emerge to the surface, that are far too regular to be of natural origin. In a submarine, Ella and scientist Konrad Martin dive to the bottom of the trench. The Challenger Depth appears to be the source of the disturbance. What they discover is a huge stone sphere, hard as diamond, that resists all common measuring methods. Suddenly, new signals occur: first from the North Cape region, then from Australia, then from Antarctica. Ella and Konrad hurry around the world, encountering the same mysterious stone formations everywhere. All of a sudden the signals from the spheres begin to synchronize. Their seismic waves generate earthquakes and volcanic eruptions all over the world - Ella is working obsessively on a solution, but the countdown is running ...

Thomas Thiemeyer, was born in 1963. He studied geology and geography before embarking on a career as a self-employed author and illustrator. His science fiction thrillers and young adult books have won numerous awards, sold more than a million copies and have been translated into thirteen different languages, permanently placing the author into the ranks of popular German fiction writers. His stories are in the tradition of classic adventure novels, often involving the discovery of lost cultures and ominous mysterious powers. The author currently lives with his family in Stuttgart, Germany.