The Woolly Mammoth Theatre Company, which has been occupied with behind-the-scenes business for most of the season, returned to the boards this past weekend with a bang.

Actually with a bang, a whimper, a demented cackle of pain and a cry of laughter.

The occasion is Harry Kondoleon's "Christmas on Mars," and with it Woolly Mammoth reasserts itself as the most original of the city's smaller theaters. This 1983 play, first produced off-Broadway, takes a nutty bobsled ride over a risibly rocky landscape of contemporary neuroses. Serving up the anxieties of his four characters at breakneck speed, Kondoleon has produced what I can only describe as stream-of-consciousness farce. It's what you might get if, say, Christopher Durang had written "Barefoot in the Park."

The first of a trio of plays that will rotate in repertory through July 31, "Christmas on Mars" also shows us four actors working in near-perfect harmony, even though the characters they are playing are at one another's throats. Indeed, these characters aren't content to trample one another's feelings. Toward the end of Act 2, Nancy Robinette, the very picture of the chic, successful, but terribly guilt-ridden mother, actually throws herself face down on the floor so that her daughter, the sweetly pouting Gra'inne Cassidy, can walk all over her physically.

In Kondoleon's view, we're living in outer space these days, if not on Mars, and anything goes as long as it helps ease the angst. Howard Shalwitz, as a giddy, gay, former flight attendant, will even find solace by curling up inside a baby's bassinet. If the madcap antics belong to farce, they are inspired by deep personal anguish. As a result, "Christmas on Mars" is simultaneously painful and blithe, hurtful and hilarious. Rather like an adroit juggler tossing scimitars and beach balls from hand to hand, director Grover Gardner proves remarkably successful at keeping the contradictory tones of the play airborne.

The setting is an empty urban apartment, nicely designed by Ronald J. Olsen so that there are more than enough corners for the characters to huddle in. The prospective occupants -- Bruno (T.J. Edwards), a narcissistic actor/model, and his girlfriend, a casting agent named Audrey (Cassidy) -- are soon joined by Audrey's mother and that former airline steward, Nissim, who was once Bruno's roommate and has carried a torch for him ever since.

The mother makes it clear that she has no intention of merely helping out with the rent; she plans to move in and make up for all the years she neglected Audrey. For her part, Audrey reveals that she is pregnant, but in no great hurry either to marry Bruno or to patch up the past with her mother.

As for Nissim, he is a total misfit who listens to records at the wrong speed and doesn't realize it, smokes imaginary cigarettes and patently refuses to face what others call facts. He, too, will move in -- although whether he expects to reclaim Bruno, act as nanny for Audrey's baby or have a child of his own seems to depend upon his whim of the moment.

The more these four try to sort out their hopeless lives, the more entangled they get. Each has revelations to spring upon the asssembled company, usually at the least opportune moment. They spat, spar, stomp off in a sulk or hug the walls -- never one another -- helplessly. "Everybody's had a flipped-out scene here. Why not me?" explodes Bruno at one point, launching another round of recrimination and remorse. And when the mother arrives with shopping bag of conciliatory Christmas presents, she ends up greedily opening them all herself.

With less deft actors, it could be a silly mishmash. But the Woolly Mammoth cast meshes like clockwork, and the breathless pace forbids you from dwelling unduly on the more rampant of the evening's multiplying absurdities. Edwards, not exactly the model type, plays Bruno as a hopped-up version of the boy next door; the performance is lively and ingratiating throughout. Shalwitz gets a little too cute on occasion, but his airy lightness as Nissim generally manages to avoid homosexual stereotyping and still communicate the flutterings of a gay heart.

Cassidy can make passivity seem an act of overt aggression. Simply with a woebegone look and her collapsing shoulders she conveys the notion that pregnancy easily eclipses the worst of Hercules' labors. The brooding is deliciously comic. But best of all is Robinette -- who plays the mother with dithery freshness, undercutting the character's abject breast-beating with wispy tones of self-mockery. The portrayal is wildly kooky, spacey even, but Robinette builds it upon the hard realities of an illogical and impulsive mind.

Like all the characters in "Christmas on Mars," she flits from one emotion to the next like a crazed hummingbird desperate to make a nest. For all their yearnings, you can't say they end up with anything remotely called a home -- only a mocking Christmas tree with faulty red lights. Kondoleon's cockeyed play takes the leitmotif of our day -- reach out and touch someone -- and zestfully rips it to shreds.

Christmas on Mars, by Harry Kondoleon. Directed by Grover Gardner. Set, Ronald J. Olsen; lighting, Steve Summers; costumes, Jane Schloss Phelan. With T.J. Edwards, Gra'inne Cassidy, Howard Shalwitz, Nancy Robinette. At the Woolly Mammoth Theatre Company through July 31.