HIS IS THE story of two people, a mother and daughter, and their long journey toward a kind of understanding - of each other, of each other's worlds and, finally, of themselves, or at least more so than when they started.

It is not, fundamentally, an unusual contemporary American story of teenagers in rags, and on drugs, of all-out rebellion, of sexual promiscuity and a relentless running after - or away from - something; of incredulous and despairing parents watching their children become tattered and sedated strangers, rejecting completely what they thought they had taught them to believe in.

Where it is different is that the mother, freelance writer Betty Wason, has writen a most candid book called "Ellen, A Mother's Story of Her Runaway Daughter." As a runaway, Ellen was one of the more than one-half million teen-agers who flee their homes each year. Although the runaway phenomenon is usually considered a symptom of the '60s upheaval, it still continues, with area county police, for example, currently reporting an average of 100 to 150 a month.

Another difference is that unlike many of the American runaways who simply disappear, Ellen Brannick stayed in touch with her mother - off and on - for the six years she was on what she calls "the college of the road." Much of the book is based on their postcards and letters, with which Wason filled one drawer of a chest.

Because of the book's frankness on such matters as Ellen's once-casual sex life - subject of some of their most heated arguments - Wason worried at times how her daughter woudl react. "Don't worry, Mother, I won't sue," came Ellen's cabled response.

Were it not for an almost built-in horror over Ellen's refuge once in drugs, her side is a compelling adventure and survival story in itself. She is in some ways representative of the well-off teen-agers of the '60s who spurned the comforts of their homes and middle-class society at large, sought an expanded consciousness through drugs and roaming the world and are settled down, for the time being , at least, into simplicity and hard work on the land.

"I had to go from having everything to having nothing," said Ellen during a visit to Washington. "I had to know what it is like to be hungry."

The reasons for running away are, of course, not that simply. But Wason, as her book shows, made a valiant attempt to understand some of them.

"During the years of anguish when I did not know from letter to letter where Ellen was, sometimes not even what country she was in. I tried to relieve my anxiety by researching the whys to this bizarre youth movement," she writes.

She traced similar movements, dating back as early as 1125 when medieval youth, most from aristocratic homes, roamed the highways filthy and unkempt, ridiculing the then establishment and preaching the reform of society through love; she read books popular among the counterculture, like Erich Fromm's "The Art of Loving" and Frank Waters' "The Book of the Hopi", she studied Eastern religions and all available literature on hallucinogenic drugs.

When she learned that drug induced trips can elicit what some doctors regard as profound spiritual insights she was better able to understand some of her daughter's religious searching, "I am convinced," says Wason now, "that there is a correlation between drug use and the '70s sudden interest in spirituality."

Wason, who is in her early 60s, lives in a two-bedroom Spanish-and French provincial-furnished apartment in Arlington, Va. Although there are the token trees and grass, the artificial flowers in the lobby, her five-story building is rooted basically in the steel and concrete of highways, cars and fast-food places.

Ellen Brannick, 23, lives for most of the year with her husband and two small children in an 18-foot Sioux Indian teepee, on five acres of near wilderness near Twisp, Wash., about 150 miles northeast of Seattle. Everywhere they look are the snow capped Cascade mountains.

This year they took a small farmhouse for the winter, rent-free in exchange for the care of the owner's two llamas, two horses, six sheep, nine goats, two cows and miscellaneous chickens, rabbits and cats.

But it was back to the teepee in May. "I'm really addicted to living in one," Ellen says. "Everything we own we can put in our (56 Chevrolet) station wagon. We aren't into material things. The only thing I'd like would be running water; electricity I can give or take. Actually, I think electricity is evil. It keeps you up late at night. Without it, you go to bed when it's dark and get up with the dawn. It's beautiful."

"I don't know how she stands it," says Wason. "They sleep on foam mattresses on the ground. Everything they own is in boxes and suitcases ringing the inside of the teepee. We would consider it a slum dwelling."

During her visit to Washington Ellen talked easily, at times almost incredulously about here experiences with drugs (started at age 14 when she and her mother were living in Pleasantville, N.Y.).

"That was a very self-destructive period of my life. I tried everything except heroin." She rattles them off, not boastfully, but with a kind of wonder about that time. "Methadone, LSD, methadrene, STP, MDA, PCP, opium, demerol, amy, nitrite. I sniffed freon for an instant LSD-like rush. I smoked harhish. A lot. You could buy it over the counter in Portugal and England." She also talked her mother into refilling several times a prescription to relieve menstrual cramps which she and her friends gulped down for more highs.

"I wanted to be stoned every minute of the day, anything to escape the dull and humdrum of school life of home, of everything. Drugs were everywhere. Pills were a lot easier to get than marijuana. But you had to be careful what you took."

Once, during a five-month hitchhiking spree across this country and Canada. Ellen was picked up by a man in his 40s who offered her some pills, as did many who gave her rides. He showed me the bottle and I knew it was a strong muscle relaxant, so I refused. Only now do I get a little scared when I think about that."

"I could never tell she was on drugs, that's what was so shocking," says Wason. "If they were smoking grass she and her friends would go into her room and burn incense to cover up the smell. They were very quiet. I thought how well-behaved, in contrast to the rowdies on beer and liquor."

Wason decided to take a house in Portugal, both to give her daughter a change of scene and to provide herself with a compatible (and inexpensive) place to write. (Her varied background includes being one of the first women correspondents in Europe during World War II, and she has, written 23 books, with topics ranging from Greek customs to Spanish cooking to home-improvement.)

After Ellen was kicked out of a private school in Switzerland for use of drugs, Wason, almost desperate now, decided to return her to the United States where the plan was that she would stay with Wason's brother and finish high school. Instead, after a quarrel over Ellen's running off to Morocco with a boyfriend, Ellen, then 15, left with the $400 in travelers checks intended for her return to the States. Two weeks later Wason received a postcard from Paris. And then followed Ellen's six-year odyssey.

Except for that initial $400 and small gifts of $50 and $100, Ellen was self-sufficient, Wason said. "I still don't know how she did it, but a woman - without being a tramp - can get by fairly cheaply. And of course, there's a whole society out there of people helping each other.

"My daughter's strong, and I guess that's why she survived."

So far as any bitterness about her daughter's duplicities and at-times indifferences to her mother's concern, Wason said she finally reached a point "where I could let her go and be herself, even though her choices would not be mine. She was determined to live her way, and she is. And that's where we began coming together again, as two women leading two different lives."

Despite their disparate lifestyles, there is a resemblance between the two women, not physically (except that they are both small) but in a canny combination of innocence and stubbornness. In the daughter it comes off as a free, almost sweet, spirit, the kind people are naturally drawn to. One senses that same spirit in the mother, only hers has been tempered by time, experience and responsibility. (She was soley responsible for raising Ellen after her former husband, Ellen's father, left home for good two weeks before her daughter was born.)

In reading their book and in talking with each of them, one cannot help but be struck also by their openness, their willingness to share their experience without embarrassment Ellen shrugs it off. "Why should there be any great secrets?" Wason says. "I am a writer - the book was my way of putting things in order."

Although Ellen doesn't call herself a writer, she is. And although she probably didn't know it at the time, her own at-once very young, very old (and sometimes drug-tinged) distillations of her dizzying leaps from continent to continent, from beaches to mountains to valleys, from hippie mecca to solitariness and back again may have helped her put things in order. And at the same time let her, as a letter can, reveal parts of a self that could have otherwise remained forever uncommunicated, particularly to one's mother, anyone's mother.

From a beach in Oregon she wrote, "My self travels far from the ocean world/but my soul lives in the sea" . . . From the Alamo Canyon of New Mexico, "Why can't we be friends and accept each other for what we are . . . I'm myself, Ellen, sand dancer, ghost dreamer, and I love you, despite our mutual disagreements."

From a cave in the Atlas Mountains of Southern Morocco, her "Shangri-La," descriptions of green wheat and clear green pools, "The sweetest mineral water to drink and the blackest, thickest and smoothest honey to eat" . . . From a communal schoolbus struggling with frequent breakdowns from New York to Florida to Nexico, "Knowing what I don't want, it is difficult to perceive what I do want" . . . From somewhere around Columbus, Ohio. "Travel on, intrepid searchers, travel on 'til the brake shoes slide off your feet and fires burn out your night journey."

From a mountain valley in California, "I have a quilt, a blanket, and all the clothes I could ever need. Life balances itself out." From Tallahassee, Fla., "Sunshine is a main ingredient in sanity."

Ellen lived in communes in London, upstate New York, in an abandoned house on the beach of Padre Isle, Texas, in Southern California (from which one letter came on White House stationery, courtesy fo the daughter of one of President Nixon's aides living in the same commune). She blackened her eyes with kohl in Morocco and went nude on the beach at Agadir. She slept on the side of the road in Mexico and on the black sand beaches of Michoacan. She traveled in a double-decker London bus through Turkey into Afghanistan. She was intent only on following her "karma" and "whatever way felt best."

One of her journals summarized her travels in 1972 with Claude (Cloud) Brannick, 26, her husband-to-be: "Portugal to Spain to Morocco (Tahrezoute) back to Spain to Portugal to France to Amsterdam to Luxembourg to New York to Colorado to New Mexico to California to Washington to Colorado to California to Washington to California to Texas to New York to Indiana to Florida to Louisiana to Texas to Mexico to Yucatan to Oaxaca."

They put together a religion which Ellen calls "a mixture of American Indian. Buddhism, a little pure Christianity and Taoism." Writer-philosopher Alan Watts, she said, was a major influence "in helping us find a calm place inside and a belief in our own power."

She worked in a ravioli factory, a bean cannery, as a secretary in a laundry, chamber-maid, charwoman, waitress, barmaid. She picked oranges for $1 an hour in the Ojai Valley of California and got her high school diploma through a University of Nebraska correspondence course.

In a long remindful of writer Carlos Castaneda's insights during walks with Yaqui Indian Don Juan, Ellen described a 12-mile walk through New Mexico's Alamo Canyon, during which she and Cloud ate only nuts and raisins, drank fresh cold creek water and smoked kanikanik, an herb used by the mountain Indians. "We didn't have to talk all day," she wrote. "We just listened, with our ears, with our minds, with our hands, with our feet, with our hearts. We just listened to the quiet Earth gently growing, dying, being, constant."

In the evening they cooked carrots and onions over an open fire, slept on pine boughs and listened to the chants of ancient Pueblo women and children around them.

Out of all Ellen's and Cloud's experiences, that was the most unforgettable. "For us," she says, "it was a very religious experience."

Once Ellen wrote her mother asking for vitamins B12 and C as a birthday gift, the lack of which had caused neuritis in her hands and problems with her teeth. In an unusual letter she wrote, "Please send me $100 immediately in a cashier's check, plus include any Christmas presents." And then came the letter explaining her new dependency. She was pregnant.

The baby was delivered by its father on a sunny July afternoon on the banks of a Washington state river, where Ellen and Cloud planned a camping trip (with all the necessary obstetrical supplies) around the birth of their child. One of Ellen's most poignant letters was written a few hours after the baby was born. She was named Omaste (Dakota Sioux for sunshine) Wakpa (river) because of their affinity with nature and the American Indians. They call her "Maste" (Mahsh-Tay) or "Sunshine".

"I'll never get used to that name," says Wason, "but I've finally come to the point where I can say 'Sunshine.'"

Ellen and Cloud decided later to be married after being together for three years. "I don't know about marriage, but Cloud and I are forever," she said once.

"I don't know if it's their sexual or spiritual life, or both, but it does seem to be a good marriage," says Wason.

Ellen had her last acid trip at 19. "I still have some flashbacks, and it ruined my eyesight. That scared me, and then just seeing others wandering around like zombies, doing nothing except listening to music, finally turned me off, and I stopped. The only 'drug' - quote, unquote - my husband and I use now is marijuana. And that not very often. You can't be stoned when you're responsible for two small children." (They also have a son. Sage, 14 months.)

"Now we can climb to the top of a mountain and get a high. Wow. Climbing without drugs. Nutrition, health, living off the land and just personal and spiritual well-being are being emphasized now. We didn't have that before. We're not the crazies we once were.

"Teen-agers - mostly farm kids - out in Washington will hardly believe my stories. For them, one beer is really risque. They're happy kids, and I think partof it is that they work really hard.The best cure for the teen-age lazies is hard work. The softer your life is the easier it is to get bored."

Wason admits she feels guilty - "although I've learned not to dwell on the past" - of that strange paradox of affluent American life. "I gave my daughter too much as a child except, perhaps, time. I was . . . am . . . a workholic, but I've had to be . . . I should have made Ellen work for her allowances . . . I made many, many mistakes. I was much too soft. I can't believe my eyes now to see how "hard she works, from dawn until she drops at night."

"I had a very privileged childhood, and I think it was like for things to be hard," says Ellen. "As an only child I had everything I wanted, but I was lonely for my mother's company. She was always working. I never had to work, except for a little gardening. And I knew that wasn't serious, because we could just walk to the store and get anything we needed. Now gardening is serious because it means food on our table."

She refuses even to buy toys for her own children. "I give Maste (age 3) a stick, for example, and man, it's a hundred things. I want them to learn to use their imagination, rather than just have things handed to them."

When it comes to talking about how she would react if her children became runaways, Ellen is less confident. "I would hope that they can find a calm place in their minds without having to run over the world," she says very slowly, "but," and here she thinks hard for a minute, "I wouldn't stop them."

She and Cloud, who earns $3 an hour with the forest service, have refused loans from Wason to buy a house. "I know it hurts her not to accept," says Ellen, "but we're determined to make our own life."

"Now that I'm beginning to see what they're trying to do," says Wason, "I can only be impressed with their courage and guts to live what they preach. If they can take this now they can take anything."

She has learned to laugh, finally, or rather chuckle at such things as her grand arrival at the grubbiest of hippie outposts (where she once visited Ellen) with her best tablecloths and sheets; at what she sees now as a false concern about appearances, about what other people would think of a daughter in hem-drooping Salvation Army clothes ("rather than paying attention to what is in her mind"); at recalling how she derided her daughter's insistence on natural foods and recycled clothes and then wrote a book on high-fiber diets and shops now herself insecond-hand stores.

But she, naturally, can't help but wonder where it all goes from here when she sees, for example, Ellen's new delight in a dishwasher during visits to Arlington, her relishing of long hot soaks in her mother's bathtub, her pondering of her own daughter's education and wondering whether she should go to a free school or regular.

"Maybe," Ellen said once, "maybe it's not good for a child ot be too different from others . . . "