In 2049, Father Ramon Ruiz-Sanchez of Peru, Clerk Regular of the Society of Jesus, is a member of a four-man team of scientists sent to the planet Lithia to determine if it can be opened to human contact. Ruiz-Sanchez is a biologist and biochemist, and he serves as the team doctor. However, as a Jesuit, he has religious concerns as well. The planet is inhabited by a race of intelligent bipedal reptile-like creatures, the Lithians. Ruiz-Sanchez has learned to speak their language to learn about them.