Reynolds (The Prefect
) is a master of fitting large-scale space opera into just a few pages, and this novella is no exception. The Mongols, led by Genghis Khan, conquered Earth a thousand years ago and now rule an interstellar civilization via a wormhole transportation system created by extinct aliens. Yellow Dog, a spy for the current khan, is sent on a mission to a distant part of the empire where phantom starships have been glimpsed during wormhole transit. Taken prisoner by the sadistic local Mongol commander, Yellow Dog discovers that the commander has collected artifacts from these phantoms, and she soon finds herself in charge of interpreting them as she investigates the appearance of several alien races with humanlike DNA. Technology, history and an unlikely friendship add dimension to the short but intriguing universe-spanning mystery. (Jan.)