"Dhrusil-matkhashi is a wasteland. The soil is sterile. Why do you suppose we stay on this continent?"

Marta, a graduate student researching indigenous life on isolationist Dray's Planet, discovers an animal that can't be indigenous, but which can't have come from anywhere else. The puzzle convinces the Children of the Second Revelation to bring two Unbelievers into their closed society. As the rival offworld scientists trek into the harsh desert to determine the creature's origins, Marta stumbles onto another mystery: why do folk tales speak of roarings and screechings from the planet's second continent, the uninhabitable Land Beyond the Gates? And why are the Faithful forbidden to set foot there?

Religious leaders will not sanction a trip to the uncharted land they deem uninhabitable. Marta must keep her expedition from coming to their attention, while keeping her difficult offworlders on task. After that, uncovering the secrets of the prohibited place ought to be the easy part. But they still have to live to tell the tale...