SPRUCE PINE HOLLER, VA. -- Andy and Ronald Mullins were walking along the Dismal River one spring day with nothing much to do; no work, not much play and little hope that things would ever change.

Down the road from the isolated canyon that has been their family's home for generations, they passed a field of dry leaves and decided to make their own fun.

They set the place on fire.

"It was just something to do, I guess," said Andy, 18. "It just come upon me that very minute. It come upon you like a bad dream.

"I just watched it burn. Lord, let it burn!" he said last week from the porch of his uncle's house trailer here in Southwest Virginia, hands raised to the clear skies and the steep hills surrounding him. "It ain't hurt nothing."

One-half acre burned that day in March 1986 before 10 volunteer firefighters -- including Andy and Ronald Mullins -- put it out.

Later in the week, the Mullinses were arrested and eventually convicted of one count each of arson. Andy Mullins was sentenced to 6 months on probation; Ronald Mullins, who ignited the fire, was ordered to perform 89 hours of community service, according to forestry records.

Arson has been a problem in this depressed coal-producing region for generations. It is, according to the men who have tried to stop it, a part of the culture in northern Buchanan (pronounced Buck-hanan) County and in other parts of this tristate region where Kentucky and West Virginia meet Virginia.

Last week as thousands of acres across the region burned, arsonists set an estimated 1,000 acres in Buchanan afire, investigators said. In 1986, 423 fires were deliberately set, burning 7,500 acres.

They used fire, investigators believe, to get revenge, to be entertained or to earn a quick buck on the $3.35-an-hour wage that the Virginia Department of Forestry pays volunteer firefighters.

"It's born in you," said Melton Morris, Virginia's chief fire investigator who was sent to this area when scores of arson fires broke out last week. "It's definitely a lack of education, or mental capacity. They have been in the same holler and lived in the same area all their lives . . . . Their uncle did it or their grandfather did it."

Morris, investigator Arthur Cox and a golden-colored bloodhound named Duchess have spent about 20 hours a day working on the difficult task of solving the crimes.

In most arson cases, the evidence has gone up in smoke. The most common modus operandi is a match or a lighter. The fuel is the dry leaves and branches at the side of the road.

Witnesses are desperately hard to come by, said Morris, because they are either part of the arsonist's immediate family and have lived together for generations in the same holler, or are neighbors who fear reprisal.

"Nine hundred percent of it {evidence} is circumstantial," said Morris. So far he has charged one 16-year-old youth with arson in one of the recent fires.

In search of clues, the investigators have interviewed about 75 people and chased dozens of leads. In the process, they have worked their way back into some of the region's most isolated communities.

Vansant, the largest town near Spruce Pine Holler some 12 windy miles northeast, is the center of their operations and the fire headquarters for the county. It is a good place to begin to understand the culture of arson, investigators say.

A hundred-foot coal elevator sits in the center of the town like an imposing church steeple, a symbol of the guiding force in these mountains.

The steep hills around here are striped with coal. Against the autumn sky, the tops of the ridges are softened by the wispy silhouettes of bare poplar and Red Oak trees.

Many of the suspected arsonists, whose average age is 16 to 25, live in the hollers, or canyons, off the main roads. The roads are dirt, few houses have telephones and running water is still not a universal convenience. Many of the hollers are littered with the carcasses of rusty, old cars and trash. Huge, expensive satellite dishes -- the county flower, some joke -- stand out amid the backdrop of poverty. About 85 percent of the 37,000 people in Buchanan County work the coal mines, or in coal-related businesses. The unemployment rate is about 18 percent, but it went as high as 30 percent in 1982 in the midst of the recession.

Large coal operations have been here since the late 1800s. Today, coal companies remain the controlling factor in a family's daily life, and one factor in the arson equation, said investigators and local fire officials.

The work is hard and much of the productive land is owned by the coal companies, not by those who work it. Contempt and powerlessness has struck back for years with a match.

"You feel a little insignificant down there," Randall Parris, a regional forester, said of work in the mines.

Investigators said some arsonists start fires just to see the mobilization, the reaction to their act.

"It's the history of many people who worked in the mines," said Cox, who is responsible for investigations in seven counties. "They figure, 'There ain't nothing worse that can happen to me than what's happened to me working in the mines today.' "

David Tolliver is the only full-time forestry official in Buchanan. He grew up here and worked in the mines for seven years. He said life in this area often does not provide a youngster with much to do, and a little fire is one way to make the day go by quicker.

He calls it the snowball effect. Last year, a garden fire was what set it off. The firefighters arrived, and so did a helicopter, which became the main attraction.

A series of small fires was set over the next few days, he said, until officials put out the word that the helicopter would not return. "They want to see you come back," he said.

Some of the people in this town, and in the area, said they believed the arsonists' motive is spite, just pure evilness. They said a little drink and a lot of anger can be combustible.

"It's just meanness," said a waitress at the Rainbow Inn, a favorite restaurant in Vansant. "It's probably some bar bug."

Up in Spruce Pine Holler, where the monstrous, rusty, aqua-blue mine towers are awkward sights against the mountains, Andy and Ronald Mullins cannot quite see how anyone would view it that way. The woods here, they said, are useless. There's not much game, a few squirrels maybe, and they figure that outsiders are not too concerned about what goes on here anyway.

"We didn't want to set the woods on fire," said Ronald, who was fined $100 in addition to the community service but couldn't afford to pay. "We just did it for a joke."

But Andy said he wasn't concerned about the woods catching fire. "It wouldn't have hurt me one bit," he said.