When 15 year old Stas Tarkowski and 9 year old Nel Rawlinson are kidnapped by rebels fighting for the great Arab leader - the Mahdi - their fathers desperately organize a search party. But the Mahdi uprising is spreading rapidly across North Africa and the chances of finding the children seem remote. Forced to rely on themselves, Stas and Nel, together with two young African slaves, Mea and Kali, escape their captors and head south across desolate country. In their search for a way home, they must battle wild animals, thunderstorms, hunger and malaria. Their journey to freedom brings them into contact with some colorful adult mentors: Kaliopoli, a displaced Greek, guides Stas through a critical encounter with the great Mahdi and Linde, an eccentric Polish cartographer, himself lost in the jungle, offers hope when Nel comes down with malaria and all hope for her survival seems lost.