Suddenly out of obscurity, to headlines across the nation," sings out Dakin Williams, as he pilots his 3-year-old sea-green Volkswagen down Highway 55. The majestic St. Louis Arch is receding in the rear-view mirror and to either side of the highway the landscape is flat and bleak with the leftovers of winter. But Williams' spirits are high.

"I think my life is beginning to shape up," he says. "It's taken me a long time to get to the point where I think I'm breaking through the line of scrimmage."

All his life, he has been the younger brother by eight years of Tennessee Williams, America's greatest playwright, who died ignobly at 71 last month in a New York hotel by choking on a plastic bottle cap. That's when Dakin Williams' phone first started to ring with inquiries from the national press, eager for details. When it was learned that Dakin was countering his brother's final wishes and having him buried in the family plot at Calvary Cemetery in St. Louis, instead of cremating him and scattering his ashes at sea, the phone calls redoubled.

Then Dakin announced that he would be contesting his brother's will, from which he had been all but struck in 1969. At stake is an estate estimated at $10 million, the bulk of which Williams left to the University of the South in Sewanee, Tenn., his grandfather's alma mater. Dakin also let it be known that he was "80 percent certain" that his brother was murdered and that he placed no credence in official explanations attributing the playwright's death to a bizarre accident. The wire services gobbled up the charges. That's when the hate mail started.

As the theatrical world was grieving the loss of its master playwright, Dakin Williams was saying, "If he had to die, and everyone has to die, he couldn't have done so at a more opportune moment." That is not the politic statement to make, especially when you've just written, as Dakin Williams has, a book titled "Tennessee Williams, An Intimate Biography." "Only a few people might have bought it before," says Williams. "Now it's going to sell 2 million copies." In light of the circumstances, Arbor House has upped the printing to a reported 50,000 and advanced the publication date by three weeks to April 30.

What's more, Dakin Williams says he's going to run for president on a ticket with Chicago Mayor Jane Byrne, although a spokesman for the mayor denies the two have ever discussed the possibility. Nonetheless, Williams has a slogan prepared, "Bring Home the Bacon with Jane and Dakin," which he delivers with an explosion of laughter, midway between a heh-heh-heh and a cackle. The raucous laugh, surprising as a thunderclap, is his most striking similarity to his brother.

The biography, opposed by Tennessee sight unseen, was cowritten by Shepherd Mead, author of "How to Succeed in Business Without Really Trying." It does not take a nasty turn of mind to suggest that the younger Williams is enacting a distasteful version of "How to Capitalize on Misfortune Without Thinking Twice."

"Of course, I am," he replies, bluntly. "It's true."

Only it goes deeper than that. Dakin's eagerness to ingratiate himself, the frankness that borders on rashness and the thirst for attention are rooted in a sibling rivalry that dates from childhood. Like the traumas in one of Tennessee's own plays, the consequences are grotesque and embarrassing. They are also mesmerizing and at moments sadly touching.

Dakin swings the Volkswagen into a modest middle-class subdivision in Collinsville, a nondescript Illinois town of 15,000 perched nine miles east of St. Louis on a bluff overlooking the dank, dark lowland they call the Mississippi Bottom. The Williams house is in the Cape Cod style--half brick, half wood with a back porch outfitted mostly with pale stained-glass windows instead of screens. A forsythia bush by the back door recently burst into flower, providing the only touch of bright color. This part of Collinsville is known as the Dieu Addition, apparently after the contractor who built the homes, although it sounds like a name Tennessee might have dreamed up. You can take a streetcar named Desire to the Elysian Fields. Or you can take a sea-green Volkswagen out to the Dieu Addition. In both places, Tennessee's spirit looms large.

Dakin Williams lives here with his wife, Joyce, a tiny quiet Texan from Big Springs with thick red lipstick, a hospitable manner and neatly styled hair the color of pink champange. Their two adopted daughters have left the nest, but Joyce's mother inhabits the downstairs bedroom, and two cats, Bartholemew and Morris, prowl the premises. The house is largely unkempt, except for the living room, tidy but cluttered with furniture Dakin brought back from two tours of duty with the Air Force in the Far East. On the coffee table are several glass figurines, but they are not there in tribute to "The Glass Menagerie."

"They're Joyce's," says Williams, as he settles into a thick couch with brown and gold Aztec-looking upholstery. He is a portly man, with a self-admitted fondness for Tanqueray gin and a bonhomie that would be somewhat more engaging if it were less intense. Since 1965, he has practiced law out of a second-story office on the main street of Collinsville. His clientele, clinging to the bottom rungs of the economic ladder, come to him with "divorces, bankruptcies, fender-benders, that sort of thing." He says their problems break his heart, but notes wryly that the average truck driver makes more money than he does.

In 1980, Williams wrote a book about the curious cases he has handled, both as Collinsville's best-known lawyer and before that as an attorney for 20 years in the Air Force. It was called "The Bar Bizarre," Tennessee provided a flattering introduction, and a small St. Louis firm published it. But it sold poorly and now there are stacks of copies in the basement of the house, even though Dakin believes it's "more shocking than anything Tennessee ever wrote."

Tennessee has always been the yardstick. Other men might settle for their own lives, but Dakin Williams has long fought for a share of the glory that sometimes bathed Tennessee in a great white light. Being a battle with genius, it was mostly a losing proposition. Their father, Dakin likes to say, preferred him over the sissified Tennessee, whom he branded "Miss Nancy." But their mother, Miss Edwina, favored her artistic son. So did their 74-year old sister, Rose, until she underwent a tragic lobotomy five decades ago that has left her to this day in a childlike state. (Dakin says that no one has told Rose that Tennessee is dead.) And for the rest of the world, Dakin felt he simply didn't exist.

The rift between the two brothers widened when Dakin returned home from World War II to discover his brother had a male lover. Dakin wrote an indignant letter, chewing him out. "Coming after our sister's insanity, it was a shocking situation," he explains. "I said it would hardly ingratiate us to St. Louis society, which I then had some hope of breaking into. Tennessee didn't mind the sexual accusations, but he found it disgusting that I'd mention my sister in such an insensitive manner. That infuriated him."

Still, Dakin turned up regularly at all his brother's Broadway openings, to be shunted aside more often than not. At the glittery parties that followed, his duty was to take care of Miss Edwina. But the big schism came in 1969, at the climax of a dark period in the playwright's life that Tennessee called "The Stoned Age." Perpetually high on speed and booze, prey to acute paranoia, the playwright was fast losing his grip on the world, and few of his companions at the time extended a helping hand. Dakin fetched him from Key West and had him committed to Barnes Hospital in St. Louis. Tennessee later remembered the three month incarceration as the most hellish experience of his life. Dakin was his only lifeline to the outside while he went through the agonies of drug withdrawal. Painful as the treatment was, Dakin maintains he wasn't about to have it terminated until a cure was effected.

"People now say I put him in a snake pit because it was near to my home," Dakin fumes. "Hell, it cost $200 a day. I saved his life by locking him up. The only difference of opinion is whether he would have lived 10 days or 30 if I hadn't put him into rehabilitation. I prolonged his life for 12 years, which enabled him to write 'Out Cry,' his memoirs, 'Small Craft Warnings' and five or six other plays, some of which will eventually be accepted as masterpieces. I contributed to that legacy. For that, he cut me out of his will.

"At the time, I was his sole beneficiary. So I lost $10 million by saving his life. And now people say I'm greedy. If I'd been greedy, I'd have let him die." The irony of the situation prompts him to another wild cackle.

"In a way, Tennessee has been good for me," he says, while Joyce half-listens, half-pages through a People magazine. "Having him for a brother has forced me to run for public office, do everything but jump off the Empire State Building. When he was in the hospital, I told him once, 'You know, Tom Tennessee's real name, reserved for his intimates , you and me remind me very much of the Booth brothers--Edwin and John Wilkes. And you know what John Wilkes had to do to compete.' I thought it was a joke. But after he got out of the hospital, Tennessee wrote me a scathing letter, denouncing me and saying I'd really revealed myself when I'd made those comments about the Booths."

By 1980, when Dakin was running for U.S. senator from Illinois, the relationship had mended to a point that Tennessee agreed to make a campaign appearance with his brother. The press turned out in force and questioned the playwright about Dakin's qualifications for office. Recalls Dakin: "He said, 'Well, he's been very good to our mother,' which didn't get me any votes at all. I suppose a lot of the TV and radio people wouldn't have been there otherwise, but he didn't take my aspirations seriously. It gave him the chance to clown around a little and get some p.r. for himself."

Suddenly, Dakin falls silent. Silence in this man, who tends to force his confessions on the nearest listener, is almost as startling as the cackling laugh. "I didn't have a lot of pleasant times with him. When he was well, he didn't want to have anything to do with me. And when he was sick, he was very disagreeable to be around. I got him mostly when he was sick. I guess you could say I got in on all of the funerals and none of the picnics."

If Dakin Williams is serious about the charges that his brother was murdered--there is a strong current of black humor that courses through the family, making it hard to tell--his convictions are anchored in the paranoia that Tennessee experienced in the late 1960s. Dakin still has one of the letters his brother sent him during that stressful period. Part of it reads: "If anything of a violent nature happens to me, ending my life abruptly, it will not be a case of suicide, as it would be made to appear." And scribbled in the margin is, "Melodramatic but true."

Dakin now believes the letter is prophetic. "Tennessee was hell on wheels, a Dr. Jekyll and Mr. Hyde. Sometimes he was a very lovely person, but cross him and you'd see a different person entirely. He could infuriate a saint. In moments like those, it would be very easy for someone to put a pillow over his face, hold him down on the floor and stick that cap down his throat.

"Stupid people think it's an accident, but nobody has ever had one of those caps in his throat in the whole history of the eyedrop business."

So it was an eyedrop cap?

"I think so," he says. "It looked like one from the picture I saw in the paper. So I went out and bought a bottle and tried to open it with my teeth. I couldn't." Grinding his jaw, he mimes the presumably fatal gestures to show how unlikely they are. It is evident that his information extends little beyond what he has read in the newspapers. Half out of futility, he's "raising all kinds of hell," because if you raise enough hell, counsels the lawyer in him, maybe the inquest will be reopened.

Whatever he doesn't know, Dakin Williams does realize the value of publicity. It is not, one gathers, just the enigma of a dead playwright that troubles him, but the fate of a book, the book he believes would have healed the breach between him and Tennessee, the book that he hopes will make him wealthy, the book in which he finally gets equal billing with his brother. But if the text is, in general, flattering to Tennessee, the writing seems to have exorcised none of Dakin's personal frustrations.

"In one sense, it's only made matters worse," he says. "Any fame I'm getting is a result of him. And what I'm trying to do is get out from under his shadow."

There is jealousy in Dakin Williams. He is the first to admit it. "I'd be inhuman if I wasn't," he says. But there is more to it than a particularly virulent case of sibling antagonism. He knows that his brother committed to paper some of the finest words in the English language and that the plays have in them the stuff that will stare down time.

If Dakin takes pride at "saving" Tennessee from self-destruction in the 1960s, he swells with equal pride at having uttered a word now and then that eventually made its way into one of the plays. He once tried to explain to Tennessee the meaning of the Chinese phrase "mei yoo ganchi," which translates literally, he says, as "have no air of concern." What he wanted to get across was the Chinese philosophy of serenity. Tennessee didn't cotton to the notion, but the phrase turned up later in "The Night of the Iguana."

"He was always looking for new words. Whenever I used one he didn't know, which wasn't often, he'd make a note of it," Dakin says.

He can't forget that both Miss Edwina and Rose served as the inspiration for "The Glass Menagerie," and that Tennessee drew on their father, Cornelius, for the character of Big Daddy in "Cat on a Hot Tin Roof," whereas he, Dakin, may figure, if he figures at all, only in Tennessee's last produced play, "A House Not Meant to Stand." The character in question is a crackpot in his sixties who keeps running for mayor in a small Southern town and loses each time.

But even that is better than nothing. Because Tennessee, he believes, is as great as Shakespeare and may even have some of Shakespeare's genes, if the tangled family tree is traced back far enough. He had him buried in St. Louis--not miles out at sea--so the faithful could pay tribute to his shrine. And if he could never get close to his brother, he can, perhaps, get close his brother's words.

For a period of about 10 years, starting in the mid-1960s, Dakin performed his own one-man show, "An Evening With Tennessee Williams," mostly in backwater towns and out-of-the-way colleges. "I called myself the star of the sticks," he says, cackling again. He'd recite Tennessee's poetry and play a few songs at the upright piano, then enact Tom's monologues from "The Glass Menagerie." "Would you like to see a little of my dramatic ability?" he asks abruptly. He gets up from the sofa, the very sofa, he has already pointed out, on which Tennessee sat the last time he was in Collinsville. He moves to the edge of the coffee table with the heavy figurines. "This is the final speech of Tom's, where the mother has just told him to go to the moon, you know, after the gentleman caller turns out to be engaged to some other girl."

He clears his throat and begins to recite. "I didn't go to the moon, I went much further--for time is the longest distance between two places . . ."

He is standing ramrod stiff, his chin jutting out and his arms rigid at his sides. His round face bears an expression of choirboy application.

"I traveled about a great deal. The cities swept about me like dead leaves, leaves that were brightly colored but torn away from the branches . . ."

It's quickly proving to be a bad reading, like high school oratory 40 years ago. The reason it's bad is that Williams knows he's delivering an important speech and he's trying mightily to rise to its importance. So he extends some words as if they were toffee and rushes others together in a cymbal crash of elocution. The jerky gestures are ridiculous, although in their failed eloquence, they are unintentionally moving. But what makes the moment truly surrealistic is that the character of Tom, the rebellious son, is really a portrait of Tennessee himself.

Now he's building to a crescendo. "Oh, Laura, Laura, I tried to leave you behind me, but I am more faithful than I intended to be. I reach for a cigarette, I cross the street, I run into the movies, I speak to the nearest stranger--anything that can blow your candles out! For nowadays the world is lit by lightning. Blow out your candles, Laura--and so, goodbye."

He stops, an anxious expression coming over his reddened face. The speech is one of Tennessee's surest bids for immortality. In the Cape Cod bungalow in the Dieu Addition, that has long been accepted. Dakin Williams wants to know something else.

A half hour later, he asks, tentatively, "What did you think of my acting?"