When Kaysen was 18, in 1967, she was admitted to McLean Psychiatric Hospital outside Boston, where she would spend the next 18 months. Now, 25 years and two novels (Far Afield, 1990; Asa, As I Knew Him, 1987) later, she has come to terms with the experience- -as detailed in this searing account. First there was the suicide attempt, a halfhearted one because Kaysen made a phone call before popping the 50 aspirin, leaving enough time to pump out her stomach. The next year it was McLean, which she entered after one session with a bullying doctor, a total stranger. Still, she signed herself in: ``Reality was getting too dense...all my integrity seemed to lie in saying No.'' In the series of snapshots that follows, Kaysen writes as lucidly about the dark jumble inside her head as she does about the hospital routines, the staff, the patients. Her stay didn't coincide with those of various celebrities (Ray Charles, Sylvia Plath, Robert Lowell), but we are not likely to forget Susan, ``thin and yellow,'' who wrapped everything in sight in toilet paper, or Daisy, whose passions were laxatives and chicken. The staff is equally memorable: ``Our keepers. As for finders--well, we had to be our own finders.'' There was no way the therapists--those dispensers of dope (Thorazine, Stelazine, Mellaril, Librium, Valium)--might improve the patients' conditions: Recovery was in the lap of the gods (``I got better and Daisy didn't and I can't explain why''). When, all these years later, Kaysen reads her diagnosis (``Borderline Personality''), it means nothing when set alongside her descriptions of the ``parallel universe'' of the insane. It's an easy universe to enter, she assures us. We believe her. Every word counts in this brave, funny, moving reconstruction. For Kaysen, writing well has been the best revenge.