Lord of DarknessRobert Silverberg
A historical novel.
In the late 16th century, young British seaman-adventurer Andrew Battell is abducted by Portuguese pirates while seeking treasure off the coast of Brazil. Shipped in chains to the steamy slave-trading colony of Angola, he is seduced and betrayed by a passionate woman, tortured in Angola's foulest dungeons, then finally condemned to death.
Escaping to the African interior, Battell begins the most frightening adventure of his life — a nightmare journey into a strange and exotic world, where, to survive, he rises to become trusted blood brother to the barbaric and mysterious warrior-king call the Lord of Darkness.