Urnud is a planet in a different cosmos in the Polycosm which has beings similar to humans. During a world war, they developed ships powered by detonating nuclear weapons against a blast plate. The largest of these ships, the Daban Urnud, was built for interstellar colonization. An Urnud military fleet has a Gan (Admiral) and ships have a tactical Captain (Prag). The third Gan of the ship received a message he perceived as coming from the past of Urnud, but which may instead have been sent by Avout at the time of the Third Sack.