There's a certain justice in the fact that Joan Rivers ends this saga of her climb to stardom with the scene that turned her whole career around, a last-minute guest appearance on "The Tonight Show." At 31, she was considered too old and too shopworn to make it as a comedian, but Johnny Carson thought she was funny and the rest, as they say, is history. Until just recently, that is, when Rivers announced she'd soon be hosting a talk show in competition with her mentor. Immediately, Carson stopped talking to her, and the "Can we talk?" lady pulled out of a book promotion tour, distraught about what was beginning to look like a nasty public feud.

It was the kind of nightmarish deflation of success Rivers claims she always expects, the perfect coda to a memoir that tells a sad tale of humiliating rejection, carefully catalogued slights and gritty obsession. There have surely been good times in between today's headlines and the rave reviews of Rivers' big break, but you won't find them here. Instead, you'll meet a woman who believes everything she's worked for could vanish tomorrow, who even after she became a headline act would clean out her dressing room every night, convinced she'd be fired before the next performance. This kind of insecurity obviously takes a lot of nurturing, and "Enter Talking" explains, usually in whiningly downbeat detail, exactly how it all came about.

The early villains were Rivers' parents, a woefully mismatched New York doctor and his status-conscious, spendthrift wife. Emotionally barren, always arguing about money, they did their best to make proper Jewish Princesses out of their two daughters. And stage-struck Joan Molinsky got enough of the message to become loaded with guilt and doubts. Hanging on to her divided loyalties, she remained a more or less permanent resident of her parents' house in Larchmont throughout her twenties, dashing off to temporary jobs and making the rounds of the talent agencies while her family conspired to divert her into a good marriage or at least a respectable occupation.

At college, Rivers fancied herself an actress, but later on, when promising opportunities came, she shied away. After a while, she gave up the theater for the even more precarious life of a stand-up comic, a choice she declares was "right for me, because in those crummy clubs I could be comfortable and endure the rejection."

"The conventional diagnosis of comics," Rivers explains, "holds that they are hypersensitive, angry, paranoid people who feel somehow cheated of life's goodies and are laughing to keep from crying. I agree, but think comedy is more aggressive than that. It is a medium for revenge." And this certainly seems to be the underlying mood as Rivers takes us from her first job as an announcer at a sleazy Boston strip joint through a parade of tawdry clubs, trouble-plagued revues and intimidatingly silent Catskills night spots (including one where her act was translated into Yiddish, so "every line bombed twice"). There is little joy in her story, and even the successes -- a jaunty USO tour, a stint at Second City in Chicago, the patronage of a maternal Greenwich Village club owner -- are tarnished by griping and bitterness.

Rivers' early romances are similarly blighted: Her first marriage, to the son of a department store manager, ended after six months; her immensely supportive Italian boyfriend, who smuggled her in and out of hotels when she had no money and diligently accompanied her on auditions, was dumped because he lacked class and ambition; a handsome "true love" turned out to be a leech; and the lyricist she wanted for a soul mate was gay. Small wonder, then, that she found her professional persona in "the loser single girl bemoaning her life," playing from what one critic called a "scream-of-consciousness script."

Although this sort of barbed, self-deprecating talk may get laughs on stage, even Rivers seems to realize that in a book it takes on a pretty dreary monotone. But "if anybody is tempted to think, Poor Joan Rivers, so insecure, so driven, so unhappy," she replies, "do not bother. Be glad for me. Thank God I am driven. Being driven is my energy source. It is my fun."

Maybe for her. But hardly for the rest of us.