One of editor-critic Knight's rare novels, this effort is more adult but much less inventive than the egregiously silly fantasy The World and Thorinn (1980). In 1998, a huge floating construction called Sea Venture, ""CV,"" is on its second voyage round the Pacific; intended as a possible alternative to space colonies, CV is unpowered yet steerable as it drifts in the ocean currents. And now, while routinely taking samples from the ocean bed, CV brings up an unusual glass meteoroid that cracks and releases an invisible, intelligent energy creature--one that parasitizes the brains of its hosts, effecting simple improvements in its hosts' nervous systems. (When the creature leaves, its victims collapse but eventually recover--though they are somewhat changed, even improved, mentally, becoming more decisive and independent and less gullible.) So, aboard CV, Dr. McNulty at first thinks he's dealing with a disease--until it becomes apparent that a single entity is involved. His efforts to trap the creature without harming its host fail. And, as the victims accumulate and panic spreads, life aboard CV degenerates into chaos--with Dr. McNulty searching for a way to destroy the creature. . . or trick it into leaving CV. Standard notions and routine development: creaky, superficial ideas in a tepid, lackluster treatment.