The star of such sentimental films as Tammy and The Singing Nun turns out to have had one of the more exciting lives of the century, stuffed with bitter moments she pulls no punches in revealing. A very poor girl from Texas, Debbie (then Mary Frances) at 16 won the Miss Burbank title by lip-synching Betty Hutton's ""I'm a Square in the Social Circle."" This led to a low-paying contract with Warner Bros. and that to a better (but still slave) contract with marvelous MGM. Debbie's descriptions of life on the MGM lot are both luscious and filled with the nuts and bolts of working at that most sumptuous movie factory. She turns the six a.m. mass hairdressing of the entire MGM harem of superstars--Liz, June Allyson, Jane Powell, Janet Leigh, Hedy, etc.--into a hymn to makeup. And then studio head L.B. Mayer tells Gene Kelly, here's your new leading lady, and martinet Kelly puts Debbie into three months of dance training from three top instructors who spell each other every two hours round-the-clock until a frazzled, distraught Debbie is before the camera and belting out ""Singin' in the Rain"" in what many see as the greatest musical ever made. Then comes the hard part: marriage to needle-needy Eddie Fisher, their friendship with neighbors Liz Taylor and Mike Todd, Todd's death, the birth of the three-headed ""Liz-and-Debbie-and-Eddie,"" which changes into ""Liz-and-Eddie,"" then ""Liz-and-Dick"" (all this is ragingly readable), Debbie's long second marriage to shoe-store zillionaire-gambler Harry Karl, her going on the road to repay Karl's debts, her two dead fetuses, stage triumphs and nightclub successes, difficulties with her resistant daughter, Carrie Fisher, and deeply unstable stepdaughter Tina, her entire savings being stolen by her investment firm, blow after blow--from which she rises, unsinkably, still singing. Just fabulous (and well-written), one of the munchiest reads of the season.