An innocent victim of a London car-bombing, Richard Grey suffers from retrograde amnesia, and while he can recall much of his life, the months before the accident are completely gone, out of touch even after a meeting with a woman who says they spent that time together. Back in London, he sees more of Susan, continuing to be disturbed by his lack of felt conviction about what she says has been their relationship and by her strange obsession with a former, abusive lover. Sue finally reveals that she has ""the glamour,"" the ability to become invisible, insisting Richard has his own ""cloud."" In Priest's handling, invisibility is less a matter of magic than a psychological state, the isolated personality taken to its extreme, and in its psychological aspect the book is most successful. Unfortunately, though, the questions of what happened to Richard and Sue, whether they were in England or France, whether the unseen Niall was with them or not, bulk up the novel and often get in the way of the really interesting issue--the whether-or-not of invisibility.