Pure "hard" sf of the finest: developing and embellishing some of the ideas put forth in One Human Minute (1986), Leto presents a disturbing, highly intelligent, and scathing account of medium-future humanity's attempt to contact an extraterrestrial civilization. When unmistakable signs of technological civilization are detected on a planet hidden inside the Coalsack nebula, an expedition--including a priest and an amnesiac--is dispatched with orders to study the aliens and make contact. In spaceship Hermes, they duly arrive near planet Quinta, where facts quickly accumulate but prove baffling. On Quinta itself, the inhabitants have set up powerful transmitters that prevent all communication by broadcasting white noise. The planet itself is surrounded by a ring of ice, as if the natives had decided to expel some of their oceans' water into space and then given up the project halfway through. An experiment, or weapon, or device, of fusion energy lies abandoned on Quinta's moon. Hermes captures two dead Quintan satellites; both are infected with virus-like molecules that probably caused the satellites' destruction. Efforts to communicate with the Quintans produce no response. Suddenly Hermes is attacked with devastating weapons; only the reactions of the computer, DEUS, and the human mastery of "sidereal engineering" (gravity control) save them from disaster. Captain Steergard is forced to conclude that two or more factions on Quinta are permanently locked in a deadly space war. Nevertheless, Steergard's orders are to make contact, and this he will proceed to do--even if it means destroying the Quintans in the process. Throughout, Lem's scientific extrapolations are nothing short of brilliant; his characters too are fully realized--including computer DEUS. There are a few minor drawbacks: an overextended and largely irrelevant prologue; the usual, and still unreal, absence of women; and frequent digressions that, while illuminating, also distract from the narrative. Powerful, brooding, fascinating work, with a frightening and urgent message for Star Wars-mongers.