Bill Largess is simply delicious as the theater critic turned pimp for vampires in the weird one-man comedy "St. Nicholas." The 90-minute play, a joint Washington Stage Guild and Source Theatre production, is essentially one long shaggy-dog story without a punch line--but as in other of Conor McPherson's works ("The Weir") it's not the destination that counts but the good company on the way.

Our nameless critic, it will surprise no one to discover, is a nasty little human being--sterile himself, envious of the artists whose lives he makes miserable, in love with his petty power. "I never took the trouble to form an opinion," he explains to the audience, "I just had one," and "I don't think I deserved any respect--but I got it! Because everyone was afraid of me."

Largess bats these sorts of satirical lines around like a cat with a large ball of yarn; I don't think I've ever seen him so relaxed onstage, so nonchalantly in control. A spry, witty actor, Largess has a certain archness that he uses to good comic effect but that can sometimes render him aloof from a play, and he's always slammed the comic ball across the net.

Here his swing is easy, almost insolent, and he sends his effects sailing over your head rather than zipping past you. Undoubtedly, much of this is due to his one-on-one relationship in this piece with director John MacDonald, with whom he's worked for many years. This is really a two-man show.

The route from theater to vampires isn't an obvious one, but McPherson makes it somehow, and the audience happily follows. After pulling a cruel and unforgivable trick on a group of actors and a director, the Critic makes an utter fool of himself pursuing one of the actresses he's mistreated. Following this disaster, he finds himself sleeping in a public park, which leads to his striking up a conversation with a vampire, who needs someone to bring lively young people to his house for "parties." Why not? As he's told us earlier, describing his journalist's life, "I was dead."

The bitter satire of journalism is the best thing in the play. McPherson must have worked for a newspaper at some point in his life. How else could he capture so well the pathetic vanity, the envy and curdled ambition? "We weren't ordinary journalists," he boasts of himself and his drinking buddies. "We had columns!" Later he reveals his honest opinion of his colleagues when he snorts, "You think I was going to surround myself with people who were succeeding?"

The metaphorical comparison of critics to vampires needs no explication. To the extent that the vampire story is the Critic's dream, it's a nightmare in which he is not only himself but also the pretentious, less-than-human chief vampire William. These connections are literary, though, rather than dramatic, and in places "St. Nicholas" wanders aimlessly, which may lead the audience's thoughts to do the same. (A story-within-the-story told by William almost stops the evening dead.)

But Largess lopes through the sagging parts of the script with aplomb. Hateful and comically put upon, his Critic is also somberly aware, and afraid, of his mortality--not just his physical death, but the death of all his hopes and decency.

The play is being staged at the Source on nights when "Inns & Outs" is not playing, and on that production's bedroom set. The Critic seems at home there--it is, after all, in a theater. With no set to aid him, Largess is well supported by William Pucilowsky's minimal but telling costume: a pursed little bow tie, a hopelessly bland sweater vest, a dull tweed jacket.

The one false note of the evening comes when the Critic announces that he is one of the five highest paid writers on his paper and that his editors adore him. Perhaps we are meant to take this, like his high opinion of his talent, as a delusion.

St. Nicholas, by Conor McPherson. Directed by John MacDonald. Lights, Marianne Meadows; sound, Brian D. Keating. At the Source Theatre through Jan. 4. Call 202 529-2084.

CAPTION: Bill Largess, putting his archness to good comic effect in "St. Nicholas."