Much intrigue and adventure in this story with a 17th century setting. Filippo has never met his father, a jeweler who set out on a business trip and never returned. The family is feeling threatened by the greedy Bernardo Pagliarin, its designated guardian while Geronimo Veroneo has been gone. A shadowy stranger visits and informs the family that Geronimo is still alive and imprisoned in Hindustan. A hefty ransom will free him. Filiipo is designated as the one to find his father and he takes a precious diamond, the Ocean of the Moon, to secure the ransom. He is accompanied by the stranger, the Mussulman, and in their lengthy, harsh journey, Filippo isn't sure whether he can trust the Mussulman or anyone else.