The Omphalos of Delphi

In this sequel to The Sphere of Archimedes, nine-year-old Oliver Abernathy and his family are trapped within one of the eight Diadems-and waiting for Donovan's return. For the adventurers traveling through the icy terrain of Greenland, the Scottish lowlands, and caves of Poland, otherworldly creatures are not the only problem, but new enemies, who amplify evil. The sphere possesses unimaginable power seen throughout history. Unlocking that mystery may prove more deadly than before. Follow along as the heroes solve The Omphalos of Delphi.