Obernewtyn is set in a world recently ravaged by a nuclear holocaust, known to the survivors as "the Great White", later said by the Herders (leaders of the new religious order) to have been sent by Lud (God) to punish humanity.
The story is told in the first-person through the protagonist, Elspeth Gordie, a teenage girl who has secret mental powers such as telepathy and the ability to communicate with animals.