The trio of adventurous pals, a man who is a scientist, a fine lady and a former military pilot are in the Indochina jungles looking for some mysterious vase that holds a metal container that is of no mundane origin.
Pirx, an experienced pilot, is hired to go on a top-secret mission to evaluate some 'nonlinears' (an experimental model of android) for use as crewmembers on future space flights. Pirx and this intriguing crew are sent out to launch two satellites into the rings of Saturn, but he is determined to find out and identify a hostile unhuman coworker among them.
During the Napoleonic wars, a Spanish officer and an opposing officer find a book written by the former's grandfather.
