Downtown on a Wednesday night: A bus driver just off duty unzips his jacket and disappears into a topless bar. Three businessmen loosen their ties and file through the door next door, catching strains of Foggy Bottom on the way up. Bluegrass. Hillbilly music, they used to call it, and some still do. Toe-tapping, spoon-slapping.

The stairs channel the three businessmen into the club, aglow with flickering candles. Lined up on stage, poised with acoustical stringed instruments (no amplification) are four men and a woman. Hesitation; for some reason the sound system is transmitting a rock radio station.

Mandolin player Dan Curtis falls out to fiddle with knobs and wires. He's manager of the division of Graymar Inc. of Baltimore that sells office copiers. He usually checks out a new sound system, but today got hung up in a rented car with a flat and no spare.

Ray Hesson, banjo, goes over to help. As manager of procurement for the National Aeronautics and Space Administration, he buys weather satellites ("space ships," he tells his sons).

Guitarist Karen Belanger watches. Five feet eight, porcelain skin, thick dark mane of hair. As a reference correspondent for the Library of Congress, she spent her day thumbing through dusty books searching for the origins of the Tooth Fairy.

Belanger is dwarfed by Ray Schmitt, also on guitar, sporting a cowboy hat and a pastel shirt that blends with the brick wall. "Maybe we should all sit down and listen to rock," says the CPA, a pension specialist for the Library of Congress Congressional Research Service.

Slight tension mounts while the audience sips drinks and munches popcorn. It's time for bass player Bradley Sams to do something. Sams just stands there in his red snug-fitting T-shirt and blue jeans. With jet-black curly hair and beard, he looks enough like Belanger to be her brother. He bartends (and bounces) nights at Charlie's West Side in Annapolis.

Sams gingerly picks up his mike cord and the noise stops. His eyes widen in surprise; when he lets go the beat resumes. Deliberately, he binds himself up in the cord. Problem solved. Cheers and applause.

"We've never played to a room full of candles before," says Schmitt, scanning the meager crowd of 44 eyes. Of course, it's still early.

The week before, at the Silver Spring Armory as guests of Country Current, the Navy bluegrass/country band, Foggy Bottom had played to a capacity crowd and a standing ovation. At DiGennaro's in Laurel, the band's been packing 'em in so tight they've had to move in extra tables nearly every Friday night for four years. There are those who can remember when things weren't always so great in Laurel. Their first night there, Foggy Bottom played to just a few clapping hands until they sent people out during the break to corral moviegoers exiting from "An Unmarried Woman" next door. DiGennaro's has been jammed ever since.

"You don't have to like bluegrass to like Foggy Bottom," says Mozie Azizi, co-owner of DiGennaro's. "Foggy Bottom has introduced bluegrass to a lot of people."

Their bluegrass differs from the traditional in two important ways. First, while Foggy Bottom's trios and quartets all follow the traditional close harmony, their pitch is lower. Traditional bluegrass is patterned after the high lonesome tenor of Bill Monroe, which dwells in the treble clef and produces a nasal twang. It's a range more more natural to women in a genre dominated by men, although the twist with Foggy Bottom is that it's Belanger's earthy contralto, with its slow, rich and even vibrato, that pulls their harmonies down.

Second, traditional bluegrass, which has its roots in Scotch-Irish music transplanted to the Appalachians, is more or less defined by an ancient set of songs, many of which amount to little more than a few repeated chords. They celebrate a time when moonshine was the drug scene, home was a farmhouse, and Mom and Dad were synonymous with love and wisdom.

Foggy Bottom gathers its material from many areas of music, including jazz ("Midnight in the Moonlight"), country ("Old Flames," "Blue Eyes Cryin' in the Rain"), rock ("Lay Down Sally"), folk ("Watchin' the River Run"), traditional bluegrass, and original compositions.

The band has been criticized for having one foot out of bluegrass, but lately there have been indications that it may be winning over some traditionalists. Bluegrass Unlimited magazine, which long has favored the older style, recently singled out Foggy Bottom's "Old Flames" as their highlight LP of the month. "They pick it hard and sing it pretty, which ought to keep our side happy while seducing the musical majority," was the comment.

On a typical Friday night at DiGennaro's almost every booth and Formica-topped table is filled. The style is country-comfortable: Over the stage is a shingled roof lined with a red-and-white checkerboard of sound paneling, in front of it a small dance floor. Ceiling fans circle lazily.

"Hi. We're Foggy Bottom, and we're going to have fun," says Schmitt. "Hope you'll stick around, because things get crazy around here after midnight."

The band breaks into a kaleidoscope of sight and sound, underscored by the syncopated staccato that makes it bluegrass. Energy is unleashed, and builds.

They take turns singing lead, Belanger with her citified mellowness, Schmitt with his "uptown" voice, Sams with his traditional vocals. They trade instruments. In "The Battle of New Orleans," Curtis and Hesson break formation and march off to war with their instruments at right-shoulder arms. In "Duelling Banjos," from the movie "Deliverance," Schmitt repeats the guitar mistake from the sound track and Hesson, grinning, echoes it on the banjo. The continuing game of "Gotcha!" brings freshness and spontaneity to the half a hundred songs presented during the evening.

In the traditional "Cripple Creek," Foggy Bottom starts with slow, harmonious vocals before switching to ever-accelerating rounds of picking. Schmitt and Belanger dig in to see who can hold the vocal ending longer, straining with rolling eyes to outlast each other. Schmitt seems to have larger lung capacity, but Belanger is a swimmer. She wins.

The band is having its own little party, and everyone's invited. "It's more than just a hobby," says Hesson, explaining the high spirits. "It's like a night out for bowling or cards." Entertaining themselves first, they capture the whole crowd. As Belanger swings into a love song, Curtis prances over and playfully puts his head on her shoulder. Typically elusive, she acknowledges him with brief and reserved eye contact, and goes on singing.

But: Two guys in the crowd have brought along a life-sized dummy, which they have seated in a chair, and for which they have bought a drink. Now and then they usher it to the men's room. As the band kicks into "San Antone Rose," Belanger her guitar and goes into the audience, mike cord trailing. She nestles into the dummy's lap and coos, "If tonight you'll be my tall, dark stranger / I'll be your San Antone Rose."

"That's why we keep coming back. It's a totally different show every time," says Robin Alexander. She, her husband Bill and two other couples have come an hour and a half early nearly every Friday night for three years, to make sure they get a front table.

"The minute I walked into DiGennaro's and heard Foggy Bottom playing 'Midnight in the Moonlight,' I was hooked," says Bill Alexander.

"People at work can tell if we miss bluegrass, because I'll be moody and irritable," says Robin Alexander, a dental assistant. "When I get my fill of blugrass, it sustains me all week."

Sully Stephens, a Crownsville dentist, plays tapes of Foggy Bottom through the headphones in the dental chair; the music overrides the drills and polishers.

Stephens and his wife Pat have taken up bass and guitar. The Henegars (Bobbie, Doug, Amy, 12, and Skip, 11) have gotten into clog-dancing; they take to the dance floor during the speedy instrumental "Reuben's Train," and win resounding applause. One of Curtis' eight mandolin strings breaks; he brings plenty because he often breaks several in a night. Before the mandolin solo, he's back in line and in tune. And so it goes.

Back at the downtown gig, the evening builds. A tax lawyer, an economist, a Capitol Hill cop, an insurance broker, a social worker, a journalist, and a photographer write requests on cocktail napkins that the waitresses drop into the already overflowing green plastic sandbox pail, labeled "TIPS," attached to Curtis' mike stand.

"Priority is given to requests on the back of a $5 bill," he says.

"I nearly died the first time Curtis walked in with his tip bucket," says Schmitt. "It's a carryover from the bluegrass back in the 50's when bands crowded around a single microphone and played for $5 per man plus tips." (Curtis is a veteran of at least seven major bluegrass bands and eight albums.) Now $250 is about the most a local bar pays, but a band can make at least two or three times that at a festival.

The bucket is also a channel of communication, helping Foggy Bottom tailor the music to the mood of the audience. Sometimes Belanger, Schmitt, or Sams will be in big demand. Some nights they want Hesson's original novelty songs, all written in two days while his wife was in the hospital for the birth of their third child in three years. The most requested song, of course, is "Happy Birthday," which they sing in an exaggerated, twangy, syncopated style.

Sams fills in while Curtis sorts requests. "Okay," says Sams. "Let's play 'Stump the Audience.' What's this song?" as he dum- de-dums his way through a few bars.

Nobody responds. "I don't know. What is it?" asks Schmitt.

"That's the Mr. Softee Ice Cream Truck song!" beams Sams.

"Why don't you do the Maxwell House Coffee song next?" deadpans Schmitt.


Then Hesson's banjo interjects with the sound of the percolator, in perfect imitation. The audience loves it.

The phone behind the bar rings. A waitress puts the receiver on the bar and whispers into Curtis' ear.

"We have to do this right now," he says. "This next song goes out to John and his bride. They're on the phone from Florida. They're on their honeymoon and want us to sing 'Watching the River Run.'"

In the middle of the fourth set, musicians in the house are invited to sit in. A couple of years ago the band was so struck by then- high-schooler David Grier's guitar "flatpicking" that they passed a pretzel basket every week until they had collected enough to send him to the National Guitar Flatpicking Championship in Winfield, Kansas. He came second among three dozen entrants, and was asked to play on Foggy Bottom's album, "Old Flames," recorded at Bias Studio in Springfield.

What's happened to bluegrass in the last year and a half seems to be the biggest resurgence ever. This spring's issue of Blueprint, "Washington's Bluegrass Newspaper," lists 68 bands playing at more than 50 clubs within an hour's drive of Washington.

Mozie Azizi of DiGennaro's has another idea. "For one thing," he says, "it's a reaction against electronics and high-tech rock. There's a thrust back to basics -- a simpler age contrasting with computer technology and microchips. For another, there's no music that has taken the nation by storm like the Beatles did in the '60s and rock and disco did in the '70s. Now bluegrass and country are moving in to fill the gap. Third, society has become more conservative. More traditional. This leads back to bluegrass -- to the old, the familiar. Bluegrass has come a long way in the last four years, but it's nowhere near as big as country." If Washington's the Bluegrass Capital of the U.S., that may just mean it's the largest city close to the Appalachian Mountains whence the music came. Where the music's headed is not clear.

Bluegrass Unlimited suggests that Foggy Bottom may be the vehicle that carries bluegrass into the big time: "Someday, somewhere, a band like this one will make the great bluegrass crossover into broad public acceptance . . . If Foggy Bottom stays together, its outstanding singing, powerful picking, inventive selection and arrangement of material, and willingness to gamble on new ideas should make it a major bluegrass band. Perhaps they'll even be the ones to break the sound barrier into hitsville."

Jerry Gray, disc jockey on WAMU-FM, echoes the sentiment. "I think you're seeing a group right at the beginning of what is going to be some real national recognition."