The InterSpecies Compact promotes trade among its member races. Displacement Gateways, transporting spacecraft between star systems, make that possible. Vital to the gateways' construction is yttrium. Vendrilla, mature enough for Compact interaction but not membership, possesses large quantities of the precious metal. In exchange for offers by Earth of technology beyond comprehension, the coastal-dwelling Durothan enslave the interior-dwelling Loche and force them to mine and process yttrium. The Loche's supreme religious leader, ensconced in an ancient mountain fortress known as God's Keep,...