If you haven't yet discovered the Woolly Mammoth Theatre Company, the time is right.

Its three-play repertory -- "Christmas on Mars," "And Things That Go Bump in the Night" and "New York Mets" -- has become the runaway success of the summer. Extended for a second time, the triple bill will now continue through August, enlivening a month that traditionally thought to be theatrically moribund.

Granted, it may seem late in the game to talk of discovery. The Woolly Mammoth, after all, has been in business for six years now, producing offbeat, sometimes quirky plays in its modest, 126-seat downtown quarters at the Church of the Epiphany. In that period, it has managed to startle, shock, amuse and befuddle those spectators who like to view theatergoing as an opportunity to stray from the straight and narrow. Still, its achievements have come by "Fits and Starts," which, prophetically enough, was the title of the first play it presented here in the winter of 1981.

With the current trio of plays, however, the Woolly Mammoth has emerged as the most professionally consistent and artistically independent of the home-grown companies that, for want of a better term, constitute Washington's struggling version of off-Broadway.

It has issued no ringing manifestoes, hurled no challenges at the theatrical establishment. While it labors under the same financial restraints that govern all our smaller theaters (its budget this season was less than $130,000), it has never cried poverty and threatened to close, as others have, if the public didn't rally with a sudden influx of cash. It has taken its lumps without rancor and enjoyed its triumphs without arrogance. All the while, it has been building a future. Now, the future would appear to be here.

At a time when repertory theater is viewed as an impossible ideal, the Woolly Mammoth is giving us on alternating nights three plays with distinct personalities, performed with admirable versatility. Not only do the actors overlap deftly from one role to the next, but in some cases they also function as director and resident playwright. The fare has been drawn from fairly disparate sources -- Harry Kondoleon's zany farce, "Christmas on Mars," first popped up a couple of years ago off-Broadway; "New York Mets" is an original post-Mamet comedy by a promising local author, T.J. Edwards; Terrence McNally's absurdist "And Things That Go Bump in the Night" flopped on Broadway 22 years ago, savaged by critics who found it sick, sick, sick.

And yet, in a curious way, all three plays are brothers under the skin. Each can be considered a preparation for -- and an expansion of -- the other two. It is, for example, entirely possible that you will be taken aback by "Things." Filled with savage bitchery and black humor, it chronicles a battle royal as fought by an incestuous family of monsters who are afraid of the dark, one another and themselves, and consequently require a nightly scapegoat to appease their raging insecurities.

But if you've already seen "Mars," you'll be far less likely to balk. Its characters -- a young male model, his pregnant girl friend, the girl's neurotic mother and the model's ex-roommate -- are also at one another's throats. Kondoleon's play, however, has a nutty lightheadedness, as if the playwright had dashed it off between whiffs of nitrous oxide. Still, the demons that possess his daffy New Yorkers -- sexual guilt, unrequited love, loneliness, emotional impotence -- are, in fact, no different from those that are driving McNally's characters to their nightly treachery.

By the same token, if you've cottoned to Kondoleon's loopy humor and the unpredictability of his dialogue, you'll be that much quicker on the uptake when it comes to reading between the lines of Edwards' "New York Mets." Edwards' misguided characters, the lowly denizens of Phil's Typewriter Repair Shop, are forever talking at cross purposes. What they're saying and what they think they're saying are miles apart. The confusions that result are funny, sad and eventually as destructive as the intentional vituperation of "Things."

You can, if you wish, trace numerous circular paths from one work to the next and back again. They all are populated by emotionally starved people reaching out to make contact. All have to do with our enduring need for a place we can call home -- be it a ramshackle office ("Mets"), a vacant Manhattan flat ("Mars") or the basement sanctuary in which the frightened creatures of "Things" try to hide from the nameless terror beyond their double-bolted, triple-chained front door. And all deal with the sexual confusions of people who know that the old, rigorous categories of male and female no longer apply, but aren't particularly comfy with the new definitions, either.

As so often happens when you cluster plays together, they begin to talk to one another, draw one another out, reveal one another's secrets. That, not simple variety, is the ultimate point of repertory. The Woolly Mammoth has quite a lively conversation going.

No less satisfying is following the peregrinations of the performers from one work to the next. Take Grover Gardner, who plays a would-be novelist and con man in "Mets" with a mixture of tinhorn confidence and little-boy loss that would gladden the heart of Damon Runyon. In "Things," he's the unwitting victim, dragged off the streets into the predators' dungeon, who finds himself wondering with a sweetness that turns quickly to clammy fear what he's doing in a white dress. You won't see him in "Mars" for a simple reason: he's directed the comedy with such seeming effortlessness that you may think the cast is improvising the whole mad affair on the spot.

Edwards sits out his own play, but his basic boy-next-door presence is put to ingratiating use in "Mars," in which he plays a narcissistic model caught up in his conflicted feelings, as if they were so much flypaper. In "Things," boy-next-door turns aggressive and you're appalled by the corrosiveness of the charm that was so appealing the night before.

Similarly rewarding shifts are undertaken by all the major performers: Nancy Robinette, who renews her appealingly droll presence with the aplomb of a seasoned improvisational comic; Grainne Cassidy, who possesses the most engaging pout since Bernadette Peters -- but watch out when she harnesses it to petty, selfish interests; and roly-poly Michael Willis, who undergoes the most astonishing turnaround of all.

Willis is cast in "Mets" as the proprietor of the typewriter shop, struggling with bluff, jovial pontifications to keep his disintegrating life in check. It's a touching exercise in futility -- the hale and hearty discovering that the flesh is not so hale and the heart is empty. In "Things," he's become an aging ruin in white face, limping toward death and complaining every step of the way. Every word out of his mouth carries a sting. People irritate him; objects bedevil him. The deluded optimist of "Mets" has soured into an unrepentant curmudgeon.

You may see acting this good at some of our other smaller theaters. But you don't see this much of it all at once. Woolly Mammoth's repertory makes the strongest argument yet that, yes, Washington does have the resources to staff a viable theater company on its own and that, no, you don't necessarily have to run to New York or Los Angeles, as the Shakespeare Theatre at the Folger is preparing to do, for worthy talent. When so many other small theaters continue to dwell in that nebulous state between amateurism and professionalism (for a long time, "semiprofessional" was the semi-apologetic adjective they used to describe their semi-awful efforts), the Woolly Mammoth's quantum leap forward is heartening, indeed.

Over the seasons, the company has earned a reputation for adventurousness with such plays as Wallace Shawn's sexually disturbing "Marie and Bruce" and Errol Bray's "The Choir," which maintained, literally, that society castrates its children. Nonetheless, it would be wrong to relegate the group to the fringes. It is daring largely in the context of Washington theater, which, except for periodic productions at Arena Stage and more recently Peter Sellars' endeavors to establish an American National Theater at the Kennedy Center, has been largely conservative in tone.

The trick, I think, is knowing just how far to go. In that respect, Howard Shalwitz, Woolly Mammoth's taciturn artistic director, seems to have understood something that Sellars in his proselytizing zeal has not: a theater should endeavor to stay one step -- not 10 -- ahead of its patrons. At its best, Woolly Mammoth challenges its spectators. Rarely does it leave them in completely the dark, wondering what the devil they just saw.

I don't want to suggest that Woolly Mammoth is the answer to everyone's dreams. In general, it favors plays that resist neat conclusions, acknowledge the essential irrationality in human intercourse and picture the world as an emotional mine field. The reassuring and the familiar are not part of its repertoire. Such a predisposition has its downside -- an insufferably shrill production of Richard Nelson's "The Vienna Notes," for example, or an adaptation of Kafka's "Metamorphosis" that in a laborious attempt to be avant-garde ended up looking rather like a dingy East European hardware store.

The acting ensemble that is so finely tuned right now has seen its share of neophytes. And while the company's quarters are pleasantly casual, they are woefully inadequate when it comes to large-cast, technically complex plays. (For months now, Woolly Mammoth has been methodically scouting the area for a new home and may spring a move on us yet.)

*Despite such shortcomings, the troupe seethes with promise. All theater groups start out with good intentions; the Woolly Mammoth has more -- a vision that it has been implementing, steadily and responsibly. The result is a company of a decidedly different stripe. Take a look. You may end up taking two. Or three, as the felicitous circumstances now allow.