The story behind the story of the historical novel "Powderkeg" rivals the lively pioneer-era chronicle of the Utah War itself.

Well, almost.Just look at the real-life cast that played a part - over a quarter-century - in bringing the epic through to publication . . . and possibly, just possibly, to the silver screen:

- A UCLA history student, now a political science professor (Brigham Young University's Richard Vetterli).

- A legendary Hollywood movie star (the aging Joel McCrea).

- A doubting, then enthusiastic actor/screen-writer (Leo V. Gordon, who wrote and acted in the war film "Tobruk," among many other credits).

- And most recently, an Academy Award-winning director and actor ("Dances With Wolves" star Kevin Costner).

Not to mention uncounted supporting players.

The involvement of so many Hollywood veterans is testament to the cinematic possibilities they saw upon discovering the little-known - outside of the Beehive State - 1857 expedition headed by Gen. Albert Sidney Johnston.

In an era of intemperate debate over slavery and secessionism, Johnston's Army was sent West just before the Civil War by President James Buchanan as an object lesson, to subdue the said-to-be-traitorous Mormons of Utah. The Mormon settlers - under an edict from Brigham Young to shed no blood and led by Lot Smith and gunslinger Orrin Porter Rockwell (the book's colorful central character) - used then-unusual guerrilla tactics to harass and slow the military force while ambassadors tried to peaceably resolve the imbroglio.

Some 30-odd years ago, Vetterli says, he researched the Utah War while working on his master's degree. His thesis was eventually published as "Mormonism, Americanism and Politics."

"The Western movie actor Joel McCrea somehow got a copy - and called me on the phone! He said, `Can you come out to my ranch in Simi Valley, I'd like to talk with you.' I said I'd be delighted.

"So I went out to his place and he said, `I've read your book. The Utah War is one of the great Western Americana stories - I can't understand why I didn't know about it before. It's truly an epic. If you'd like, I'll put you in touch with people who will help you, and I think you can one day see this on the screen.'

"He convinced me right there," Vetterli says.

McCrea presented Vetterli to a producer and unit manager, Col. Harold Knox.

"I gave him a copy of the book. He read it - and his reaction was the same. He said, `I'm going to introduce you to a prolific screenwriter, but someone who is also a character actor - so you get a double benefit: He can feel the (roles). And that was Leo Gordon."

Gordon, a busy man in the late '60s and early '70s, reluctantly agreed to read the history book. But he too was enthralled by the big-screen potential of the Utah War. Still, he couldn't dive into a new project at once.

A few years later, however, on a handshake, Gordon and Vetterli began a screenplay. Vetterli lived in Pasadena at the time, Gordon in Sunland, Calif. The historian would drive over to the actor/writer's to develop their project and go over and over and over it.

"We worked on it for some time, and I saw him becoming more and more concerned. Finally he said, `Look. The characters in this are so complex, and you have to keep several movements going at the same time in the story. There's only one real answer to this: We must write a book. This must be a novel first so we can study the characters and bring the different elements together for the finale."

And so the "movie" about the Utah War began its metamorphosis into "Powderkeg" the novel.

Writing progressed slowly through the 1970s. "I was working on my doctorate, and he had one screenplay after another, one acting role after another," Vetterli says. Then, about 12 years ago, halfway through the book, Vetterli was invited to teach at BYU.

"Powderkeg" became a long-distance partnership. "We would write and send it through the mail, and the other would rewrite and send it back. If necessary we would call on the phone.

"My wife would laugh because we'd talk on the phone as if the characters were there. `No, no, no, Porter Rockwell wouldn't say that,' or `Anne McCutcheon [the fictional love interest . . .T would do that.'

"It got to a point where `Powderkeg' was the passion of our lives. . . . And if the book sells well enough to pay for our phone calls over the years and the mail, it will be a success," Vetterli jokes.

The book, although based on historical events and real people, also owes much to the West of dime novels and Hollywood (for Gen. Johnston, think Henry Fonda in "She Wore a Yellow Ribbon," and for action "Gunfight at the O.K. Corral"). In a note at the front, the authors of "Powderkeg" forewarn readers that the tale "blends truth and fiction."

The plot takes on additional spice with Vetterli and Gordon's expansion of an antebellum conspiracy theory.

Johnston was a Southerner. Secretary of War John B. Floyd was a Southerner. Southerners could bolster their incipient Confederacy immeasureably by taking the Southwest and California with them should secession actually occur. Utah - with a rebel general in place - could be the first Western domino to fall in a war between the states.

They also focused in on legends like "Wild Bill" Hickok and a 13-year-old William Cody - "Buffalo Bill." And these are not simply name-dropping fictional devices. Both actually served in Johnston's Utah Expedition. "They were really there. Hickok really did save Cody from being beaten up by a brute, and they really were close friends 'til the day Hickok was killed," Vetterli says.

Suddenly, after so many years of glacial progress, the novel was finished. A friend suggested they send it to Presidio Press in California, and the publisher snapped it up. Even before "Powderkeg" was officially off the presses, review services picked up proof copies at a New York book fair and gave it a good send-off.

"Screenwriter Gordon and historian Vetterli team up effectively to produce an absorbing Western in which the open-air action is nearly overshadowed by politics and personalities - from Brigham Young to James Buchanan to Wild Bill Hickok," said Kirkus Reviews. "Very well done."

"An important moment in antebellum history is effectively re-created through appealing characterizations and the judicious use of background detail," said Publishers Weekly.

Gordon's agent, Scott Penny, also sent a few copies to large agencies in Hollywood. One read it and decided "Powderkeg" would be a perfect vehicle for Kevin Costner. Costner's company, TIG productions, and Warner Bros. took out an option on the book for a screenplay.

Publication, good reviews, a word-of-mouth growth in sales, and the interest of Kevin Costner.

"It happened so quick I'm still in shock," Vetterli says.