The testimony of a defector will always be suspect and Maria McGuire who denounced the IRA after a year of full-time revolutionary activity is admittedly just that. Eventually she says she ceased to believe in the ""sterile and murderous campaign"" which continues to take so many civilian lives in Northern Ireland and fled the country. But before her disaffection with the terrorism -- which she blames largely on the Provos' Chief of Staff, Scan Mac Stiofain -- reached the breaking point, she participated in some of the IRA's most daring exploits including a junket to Amsterdam where a sensational deal to purchase Czech arms fell through in a blaze of publicity. Until she despaired of the Provos' refusal to look for a political solution she was privy to the power struggles within the organization and she airs them as candidly as she does her love affair with her accomplice in the Amsterdam arras purchase fiasco. The reasons which made her eventually abandon the Provos are perhaps less interesting than those which drew her -- a middle-class Dublin University graduate from a family with no Republican tradition -- to join them in the first place, and her very careful chronology of the confused and bloody crescendo of events in Belfast and Derry makes this a compelling, if partisan, book for anyone interested in the philosophy and organization of the oldest guerrilla movement in Europe and the long tradition of ""glorious failure"" still carried on.