Episodic alien-visitation yarn, the expansion of a 1988 short story, from the talented, erratic British author of God's World, Chekhov's Journey, Whores of Babylon, etc. When insect-like alien ``Flies'' descend upon Earth, claiming to have come in order to ``remember'' the planet, body-language expert Charles Spark is brought in to decipher the alien's purposes. The Flies study Rome intently and in turn are studied by nuns, secret agents, psychics, and Charles. Turns out that the Flies discharge their memories into hormone-jelly-filled tanks, where the memories are impressed upon the universal information- field and thus are preserved forever. But then, as the Flies depart, the city of Munich vanishes, only to turn up on Mars, where some survivors take refuge inside a submarine in a museum. A huge international expedition brings the protagonists to Mars; during the voyage, experiments with the hormone jelly evokes a godlike entity that snatches up the experimenters, all women, and conveys them to the Flies' home planet; here, they must come to terms with being immortal though trapped inside the Flies' memory store. A triumph of style, what with the novel's five parts each told from a different point of view, and plenty of stimulating and intriguing ideas; but also dense, hard to follow in places, and fragmented. Impressive, then, but far from easy and not entirely rewarding.