DISPLAYING its newfound mettle, the Round House Theater tackles British playwright Joe Orton's outrageous sex romp "What the Butler Saw," with mixed results.

As one character sums it up, Orton's final farce includes "incest, buggery, outrageous women and strange love cults catering for depraved appetites -- all the fashionable bric-a-brac." But the Round House production settles for being merely naughty when what this show needs is a touch of nasty.

Orton sets off an escalating delirium of compromising positions with a matinee dalliance in a doctor's office. While interviewing his nubile new secretary, Dr. Prentice gulls the girl into stripping and reclining in his bordello-like examination alcove. But his wife walks in, and Prentice's frantic attempts to cover up snowball into disaster. (Prentice is unaware that his wife is herself being blackmailed by a bellboy armed with indiscreet hotel room photos). Further confusing matters is Dr. Rance, a pompous clinical inspector representing the government ("your immediate superiors in madness").

"Why are there so many doors?" Rance asks on entering Prentice's clinic. "Was this place designed by a lunatic?" The doors are an essential element -- there are 142 exits and entrances, timed to the split-second. The doors are fine, but set designer Richard Young has overdesigned the clinic, a busy, overpowering melange of curves and angles and lines in incongruous Miami pastels.

Orton's characters all follow their own bent logic with determined tunnel vision, and they are at their funniest when they don't realize they're being funny. But the Round House cast doesn't have the knack for that insouciance, mugging and winking to make sure we get the joke. Played broadly like this, "Butler" comes off as a Benny Hill burlesque, a chance to glimpse familiar Round House actors running amok in skimpy underwear.

Directed by Max Mayer, the production scores with the most obvious sight gags but misses much of the subversively clever comedy of ideas beneath the pratfalls. Mayer is faithful to Orton's stage directions and restores Orton's original ending, a bit of phallic rudeness about Winston Churchill. But the intricate comic bits haven't jelled yet and the evening runs out of momentum long before the triumphantly absurd deus-ex-machina conclusion.

WHAT THE BUTLER SAW -- At the Round House Theater through March 30.