Charles Busch Celebrates a Theater Diva

Not many actors know more about divas of the stage and screen than Charles Busch. He's played a few of them himself.

But Busch is sitting out ''Our Leading Lady,'' content to be the author and not the star of his new play, now on view at Manhattan Theatre Club's tiny Stage II. This latest Busch effort is an odd bit of historical folderol, overextended and uncertain in tone but containing enough entertainment, comic and otherwise, to make an MTC visit worthwhile.

The diva in question is Laura Keene, portrayed here by Kate Mulgrew. Keene is something of a theatrical footnote. She was appearing on stage at Washington's Ford's Theatre in a comedy called ''Our American Cousin'' the night Abraham Lincoln was shot in April 1865.

In her day, Keene was a giant star, an actor-manager, running her own company, which traveled the country. And, as played by the marvelous Mulgrew, she is extravagant in action and articulation. ''We theater folk have an unfortunate tendency toward offstage histrionics,'' says Keene during one of the play's more impassioned moments.

Well, yes. We wouldn't have it any other way in a Charles Busch play, where heightened language and even more heightened emotions drive the evening. Director Lynne Meadow manages to keep things under control even though Keene's troupe is an excitable, eccentric collection of performers.

There's Keene's faded rival, Verbena De Chamblay (the delightful Kristine Nielsen) and her foppish husband (Reed Birney) who seems to show more concern for a young male understudy (Billy Wheelan) than for his wife. Add a dotty older actress (Barbara Bryne), a perpetually tipsy ingenue (Amy Rutberg) and a leading man (Maxwell Caulfield) who is carrying on with Keene, and you get some idea of the battles that will preoccupy the play during much of its messy Act 1.

Things change with the gunshot that ends the first act, and the plot turns a mite more somber as the actors are held for questioning about Lincoln's assassination. This sudden switch is disconcerting as Busch puts aside camp for some serious moralizing on the nature of duty, particularly when it comes to the theatrical profession.

The playwright has a great deal of affection for these troupers, particularly Keene, a strong woman whose single-minded determination lifted her from poverty to stardom.

Keene is assisted in her endeavors by what is supposedly her Chinese servant, portrayed with authority by Ann Duquesnay. The woman actually is a runaway slave, who had hidden her identity for years, and now, with the end of the Civil War, wants to return to the South and find her family.

Busch is best known for such camp fests as ''Vampire Lesbians of Sodom'' as well as the more mainstream ''The Tale of the Allergist's Wife,'' which moved from Manhattan Theatre Club to Broadway. ''Our Leading Lady'' is caught somewhere between the two, an adventurous play still seeking a consistent style all its own.