The enduring popularity of Katharine Hepburn is surely among the more agreeable mysteries of American popular culture. By the prevailing standards of Hollywood she has never been either beautiful or sexy, and she has never played by the rules that movie stars are expected to follow, especially those who came along when she did, in the 1930s. "I have an angular face and body," she has said, "and I suppose an angular personality that jabs into people." It is neither a physique nor a personality calculated to win an adoring following.

Yet an adoring following is precisely what Hepburn has, and has had for the half-century she has been in the movies. From the crisp romantic comedies of her early career to the meatier films of her middle and late years, Hepburn has been one of the most loved and admired of American stars. Now, in her late seventies, she has gone beyond mere stardom to become both a popular legend and a cult figure, "The theater and film's grande dame, a staunch survivor of indomitable strength whose very presence inspired courage."

That is Anne Edwards' judgment and, like many of the judgments offered in "A Remarkable Woman," it is couched in overheated prose. But it also happens to be true. The prickly young actress who startled Hollywood with her forthright opinions and peculiar behavior has mellowed over the years into a serene, confident woman whom millions admire not merely for her performances but also for her humor and grit. Even when she appears in inferior films -- and she hasn't had a really good one since "Long Day's Journey Into Night," more than two decades ago -- she brings people into the theaters, not to watch the particular movies but to see the great woman herself.

Such adoration is what she yearned for as a girl, but her achievement of it has to be one of the more improbable successes in show business history. She came from a prosperous Connecticut family with a long history of eccentricity but none of theatricality; she had an imperious, willful manner that offended other actors and infuriated directors; her aristocratic accent and bony figure were utterly out of sync with Hollywood style; and as for her looks, when she first appeared on the RKO lot in 1932 -- David O. Selznick had just signed her for $1,500 a week -- there were cries of "Ye gods, that horse face!"

But what she most clearly had, Edwards argues, were charm and "an abundance of that other indefinable quality, class." She also had "that intangible something that movies call 'star material.' " She loved the camera, and the camera loved her; disbelievers are advised to run "The Philadelphia Story" through the video machine, and to watch once again as the camera softens that angular face and imbues it with a quality that could almost pass for beauty.

As that movie was the climax of Hepburn's long series of comedies -- it appeared in 1940, and was her 16th film -- so too "The African Queen," which was released in 1951, was a major turning point in her career. With her performance as the doughty Rose Sayer, a new Hepburn emerged: "The Bryn Mawr society-girl image had been replaced forever by one of a more mature woman, a person who had the strength to endure the worst hardships and survive as ably as any man." Fifteen more films were to follow it, but not even the best of them could match this most accomplished of all her pictures, the one in which she etched herself most indelibly, and endearingly, in our consciousness.

That there were only 15 films in more than three decades is explained in large part by Hepburn's intense involvement with Spencer Tracy. This celebrated romance gets inconsistent treatment from Edwards, who repeatedly refers to it as an "affair" yet at one point coyly notes that "no one but them will ever know" whether it was anything except platonic. Hepburn herself no doubt would say that it is none of our business, which certainly is true, but Edwards' blend of gossip and deference in this and other personal matters makes for a lumpy pudding.

The same can be said, though, for just about everything else in "A Remarkable Woman," not excepting its inane title. The book did not have Hepburn's cooperation, and Edwards is curiously silent about her sources; at times we are given Hepburn's thoughts and at others conversations are repeated verbatim, but where all this came from, who knows? As if in compensation, Edwards treats the reader to the most thoroughly unnecessary barrage of footnotes ever fired; almost every person who appears gets a footnoted mini-biography, even if that person be so thoroughly known as Howard Hughes, Amelia Earhart, John Ford or Humphrey Bogart. For some reason Franklin Delano Roosevelt is spared this treatment, but that oversight surely can be corrected in later editions.