For a century, the Cloud City of Stratos that hovers over Ardana has been abandoned, left only as a curiosity and a museum piece following the brutal civil war between the City Dwellers and the Troglytes. Now the city is starting to fall, and it's up to the S.C.E. team on the U.S.S. da Vinci to keep it from crashing to Ardana's surface.

However, there's more to this than the usual engineer- ing conundrum. Relics from Ardana's past provide obstacles -- from a parasite that invades Fabian Stevens's brain to a booby trap that endangers Bart Faulwell's life, and þnally to the S.C.E. being caught in the cross þre between two opposing factions, whose disagreements may cost two da Vinci crew members their lives!