Spero Copia is a 14-year-old apprentice living in a secretive cave nation called the Sanctum, on the planet Petra. The Sanctum was founded 140 years ago when Spero’s blue-skinned ancestors, the Azurians, fled from their green-skinned overlords, the Verderians. Azurians are very spiritual people, deeply invested in building what they call the Complexus, or the link between one’s ancestors and one’s descendants. They consider themselves historians, builders, and thinkers. The Azurians anciently oppressed the Verderians, and now the tables have turned. Before Azurian history could be completely wiped out, about 500,000 Azurians escaped from the mainland, and entered the cave system in the deep South, not far from the South Pole. Now the Sanctum is a bustling, industrious city. Spero’s father is a Mede, which is a dual role of spiritual healer and physician. Spero works under him, hoping to one day be a surgeon and a Mede like his father.