When the plot is scrambled, don't worry about details; Exquisite Torture. Play written, directed by, and starring Charles Ludlam.

Is it a joke? The Ridiculous Theatrical Company, normally a carefree bunch, has discovered a new form called ''post-structuralism.''

The troupe describes this as ''a theater of pure emotion.'' And sure enough, its latest play is subtitled ''a romantic ecstasy,'' defined as ''a new genre, a vehicle for overly emotional acting.'' As usual, the author, director, and star is Ridiculous honcho Charles Ludlam. It runs through Nov. 14 at the group's theater in Greenwich Village.

Leaving aside the portentous terminology, ''Exquisite Torture'' turns out to be squarely within the Ridiculous tradition. The action zooms from one absurdity to another, glued together by its own energy and Ludlam's manic performance in the leading role. Though most of the action is clean enough, there are some lapses in taste that would call for an R rating if this were a movie.

The only innovation is the surreal slant of some scenes, which have a skewed logic that's distinctly dreamlike. The plot is slim but gnarled, involving Nero's last descendant (played by Ludlam) and a gaggle of secondary characters ranging from a beefy housekeeper to a long-lost love. Like the old movies it sometimes parodies, the action flows without a break, pausing only long enough to catch its breath between scenes. It's not a classic Ridiculous evening like the recent ''Reverse Psychology,'' but Ludlam is in good form, and that answers for a lot all by itself. No joke.