In the deep future beyond the burn line of the Anthropocene and the extinction of humanity, the city states of an intelligent species of bear have fallen to a mind-wrecking plague. The bears' former slaves, a peaceable, industrious and endlessly curious people, believe that they have inherited the bounty and beauty of their beloved Mother Earth. But are they alone? After the death of his master, a famous scholar, Pilgrim Saltmire vows to complete their research into sightings of so-called visitors and their sky craft. To discover if they are a mass delusion created by the stresses of an industrial revolution, or if they are real - a remnant population of bears which survived the plague, or another, unknown intelligent species. Risking his reputation and his life, Pilgrim's search for the truth takes him from his comfortable home in the shadow of a great library to his tribe's former home on the chilly coast of the far south, and the gathering of a dangerous cult in the high desert. Whether or not the visitors are real, one thing is certain. Pilgrim's world and everything he thought he knew about his people's history will be utterly changed.