NO DOUBT it will come as a surprise to many readers, but Patricia Hearst has written a very good book. With the professional assistance of Alvin Moscow, she has put together a clean narrative that begins in the sunlight of her happy, privileged childhood, plunges quickly into the long darkness that followed her kidnapping by the Symbionese Liberation Army, and emerges at last into the light with President Carter's commutation of her seven- year prison sentence.

Obviously she is not without her ulterior motives for assembling this long chronicle; she wants to clear her name once and for all, to regain the public sympathy that was hers until the day she was photographed carrying a gun while participating in a California bank robbery. But though she is entitled to sympathy, she refuses to grovel or beg for it. The strongest suit of her book--and it has many --is its calm, insistent candor; this is what it was like, she is saying, and she asks only that she be judged on the facts as she presents them.

Try to imagine what happened to this bright, pretty, lively, 19-year-old girl. Almost completely without political interest, a student at Berkeley largely because her fianc,e was there, she was abducted on the evening of February 4, 1974, from her apartment; her captors were members of one of those Looney Tunes fringe groups that Berkeley nurtured even after the fires of '60s radicalism had been banked. She was shoved into the trunk of an automobile, driven off into the night, then dragged into a house and heaved into a closet. She stayed there 57 days, blindfolded:

"The inside of that closet stank. I was alone there with a stale, musty odor of body sweat and filth. For all the air circulating in there, I might as well have been in an underground coffin. Curled up, I lay there in a corner, weeping. Tears flowed of their own accord, soaking my blindfold and running down my face. . . .

"Alone in the closet with that awful, pervading smell, I cringed in fear. Never had I felt so degraded, so much in the power of others, so vulnerable. What made it worse was that I could not figure out these people who had abducted me; I rarely understood what they were saying and I did not now how much of it to believe. My first impression was simply that they were crazy, insane. . . ."

That first impression was correct, though for a while Hearst--under the pressure of what the shrinks call "coercive persuasion," or blackmail--came to fall under their spell. The "army" that had taken it upon itself to liberate America from the capitalist pigs consisted of eight people: Cinque Mtume, the black "General Field Marshal of the Symbionese Liberation Army," and his seven worshipful white followers, most notable and notorious among them Bill and Emily Harris, a.k.a. Teko and Yolanda.

That was it: eight certifiable zanies, skulking about from "safehouse" to "safehouse," squeezing out a marginal existence on such funds as they could beg, borrow or "expropriate," mean and loathsome creatures who would never have been heard from had they not kidnapped the daughter of one of America's wealthiest and most prominent families. Patty Hearst was their ticket to headlines and air time, and they cashed her in for all she was worth.

For her part, she had the good sense to realize, early on, that her own ticket to survival was to go along. She had been thrust into an utterly alien world from which there seemed no reasonable prospect of immediate escape. Since she had plenty of reason to believe that physical or rhetorical resistance could lead to her death, she decided that the wisest course would be to submit to the demands of her captors and to pretend to be converted to their scrambled ideology.

Sex was among those demands (though not as frequently as the public suspected) and she submitted to it: "I lay there like a rag doll, my mind a million miles away. It was all so mechanical and then it was over. I said to myself, rationalizing again, 'Well, you're still alive.'" She tells what happened and when, but she declines to go into detail; readers looking for clinical thrills will have to go elsewhere. She is able to look back on these moments, which clearly were in no way pleasant, and dismiss them with a rueful shrug; she survived.

Similarly, she survived the robbery of the Hibernia Bank and she had the incredible good fortune to be out of the Los Angeles "safehouse" when it proved most unsafe and all the SLA members except she and the Harrises were killed in a shootout with police. Up to the time of the robbery she had gone through the motions of SLA loyalty: accepting the name of Tania, mouthing all the obligatory political claptrap, participating in the pseudo-military drills and exercises. She went through the motions in the robbery, too, knowing that to refuse was to risk death. But the robbery made her a suspected criminal, and that changed her life momentously; under the tutelage of Cinque, she developed a "certainty that the police and FBI would not hesitate to shoot me." She became "a soldier in the SLA" not out of any genuine political conviction but out of a fear that she had nowhere else to go.

There was a moment in Los Angeles that provided startling proof of the degree to which fear and "coercive persuasion" had taken control of her mind. The Harrises, shopping in Los Angeles, got into a contretemps with a store clerk. There was much scuffling outside the store; the Harrises were on the verge of being seized and held for arrest on shoplifting charges. But Hearst, at the wheel of the SLA car, fired her gun over the heads of the milling crowd. Instead of using the confusion of the moment to make her escape, she enabled the Harrises to make theirs--to run to the car and drive away.

This was not the act of the "flaming, bitter revolutionary" that millions of Americans had by then concluded Hearst to be. It was an instinctive reaction--not to save the Harrises, whom she despised, but to return to the known instead of the unknown, the SLA instead of the police. By this point Hearst had lost any sense of the reality of her past; she had no reason to expect that anything except a violent, dangerous life in the company of her captors was in store for her. Since she had months ago decided to "concentrate on staying alive one day at a time," sticking with the SLA seemed her only plausible course.

But the American people denied her the charity of attempting to understand the awful complexities of her situation. After the bank robbery and the shootout, she was transformed in the wisdom of public opinion from abused heiress to violent revolutionary. She recalls the mail she later received at the San Mateo County Jail:

"By far most of the letters I received condemned me outright--not for robbing a bank, but for being so ungrateful and mean to my parents, for deserting my country and my heritage, for the unmentionable joys of sex with black men and hippies, and, in short, for being such a rich, spoiled bitch. I had thought that reading my mail would help pass the time. But those vituperative, angry epistles were hard to take. For the first time I realized how hated I had become. In fact, it had never dawned on me how much people seemed personally to care about my kidnapping and my days with the SLA. After a time, I agreed that the letters should be delivered to my lawyers; I did not want to see them anymore."

The attorney general of the United States, William Saxbe, took it upon himself to pronounce her a "common criminal." That set the tone not merely for the broader public outcry, but for her treatment by the law after her arrest. The government was determined to make an example of her, a sacrificial victim:

"In my estimation, the whole trial was a farce. The Hibernia Bank robbery seemed to have been forgotten. It was not mentioned for days and for weeks at a time. It was the media image of me on trial. I was portrayed as the symbol of the rebellious, radical youth movement of the Sixties--the ultimate child of the Sixties. But it was all so far-fetched. I was not a child of the Sixties; I was but a child, literally, in the Sixties. In 1960, I was six years old."

That the government concentrated so single-mindedly on getting her convicted--it was clearly far more interested in her than in the Harrises--is evidence enough of its determination to punish her for violations of conventional morality; that none of these violations was voluntary was dismissed, by prosecutors and judge and jury alike, as irrelevant. She was the chosen victim of a society too swept up in its moral righteousness and smugness to bother with such niceties as terror, coercion--or truth.

Of the life she now lives, she says: "I do not live in fear. It is just that I feel older and wiser now, more disillusioned in my feelings about my fellow man." By this she means not merely the possiblility that a knock on the door can propel an innocent into the depths, but also the punishment that an unjust world can cynically impose upon that same innocent person. She is cynical about her fellow man, and she has every right to be.

Yet Every Secret Thing is not a cynical book, not really even a bitter one. In the end Patricia Hearst is triumphant. Her captors are dead or in prison; her accusers have been silenced by the commutation order handed down two years ago by President Carter. She has found a new life that includes a husband and a child, she has returned to the embrace of her family, and she has become again what she was: a sane, sensible, good- humored young woman. She is a remarkable person; Every Secret Thing is vivid testimony to her strength, resourcefulness and courage.