From versatile Scottish writer Banks, another sf yarn about the tolerant, diverse, far-future Culture (The Player of Games, 1989, etc.). The Culture is subtly controlled by prodigiously intelligent artificial Minds, who, Banks intimates, spend most of their spare time navel-gazing. Here, a huge, enigmatic object referred to as the Excession appears in space and interacts with the Culture's energy grid in ways previously considered impossible. Diplomat Byr Genar-Hofoen of the Department of Special Circumstances is sent to investigate--but, sidetracked by beautiful, talented, spoiled-brat operative Ulver Seich and by old flame Dajeil Gelian, it will be a long time before he draws near the object. Meanwhile, certain Minds occupying a vast array of self-controlled spaceships suspect that still other Minds are involved in a conspiracy--but to what end? With the Culture thus distracted by the Excession, the cruel, dangerously expansionist alien Affront seize the opportunity to hijack a Culture battle fleet and start a war that they only gradually realize they've been suckered into and can't possibly win. Brilliantly inventive and amusing--whole sections read like strings of knowing jokes--but a mess: Chattering spaceships with splendid if confusing names (e.g., Not Invented Here and Shoot Them Later) don't compensate for the absence of real characters.