Congo

A 24-year-old ERTS mathematician and strategist who leads the second expedition into the Congo, racing a rival consortium to a source of valuable diamonds.

A primatologist who has taught a gorilla named Amy to communicate in sign language, and who joins the expedition in part to continue his research into primate language.

A lowland gorilla trained by primatologist Peter Elliot to communicate in American Sign Language, with a vocabulary of several hundred signs; she accompanies the expedition into the Congo.

A seasoned mercenary with a disreputable reputation, hired as the expedition's guide to lead the team safely through the dangerous Congo rainforest.

The head of ERTS, who orchestrates the expedition from company headquarters as the firm races a rival consortium to the diamond source.