Rear Admiral Gale Harkness's ship, the Argos, under the command of Captain Bernice O'Reilly is despatched on a mission to discover the fate of two remote outposts of humanity that have gone silent. To discover that both colonies have been totally obliterated, with the exception of one young girl, is a shock in itself, but when Gale and her crew are assaulted by hurricanes, earthquakes, and volcanoes that seem to have no basis in nature, she has to ask whether an alien intelligence is involved. Narrowly escaping from an artificially produced Nova, the crew of the Argos discover a moon that shows the remnants of a nuclear explosion and some intact artificial structures. The landing party is forced to abandon their ship and as a result become marooned. What they find provides answers to many of their questions, and who or what the Taldi'na are, is finally revealed.