Two empires on the one continent of Ter are locked in combat. With endless drafts, wartime economies, and constantly shifting borders, the world knows no peace.
Except those that live on the approximately four hundred independent cities orbiting the earth. Perched on Roropa - giant floating creatures - they are self-sufficient, tight knit communities. They land on Ter once every twenty years or so, and many of their inhabitants have never set foot on solid ground. Each has developed its own religion and way of worshipping their host Roropa, and most maintain strict neutrality, prizing the peace of their own microcosm above all else.
Their peace is threatened as both empires, with rapidly advancing military technology, set their sights on domesticating the Roropa as war machines.
A thousand years ago, the greatest city sitting the back of the largest Roropa disappeared into space. It was fifty kilometers across, with forests, streams, and large, wild mammals like those that only exist on Ter today. The city achieved something no city today has achieved: communication with their Roropa and channeling of its enormous energy.
Everyone thought it was just a bedtime story, until it was sighted again.
People from Roropa and Ter alike seek to find the Lost City of Lantos, whether to control it, protect it, learn its secrets, or destroy it.