Boyd Gaines is an actor in films, but with four Tonys—his most recent for his role in the revival of "Gypsy"—his career highs are on the stage and largely on Broadway. There, he is a director's dream, versatile and with a malleable stage presence that fits a variety of characters.

Now, he's a director, too—and excellent.

Gaines makes his directing debut at Bucks County Playhouse, where he's staging Charles Busch's comedy of misled sophisticates called "The Tale of the Allergist's Wife." And even with an emergency in the production—the very-last-minute dropout of a key actor—Gaines' production comes off as smart, fluent and fun.

When I saw it Saturday night, Gaines was pacing in the back of the house behind the sound control board, and Busch, the playwright whose edgy works include "Die, Mommie, Die" and "Psycho Beach Party" (both the plays and films), was in an aisle seat toward the front, having what appeared to be as good a time as the rest of the audience.

Gaines needn't have paced, because it's on stage that the real pacing matters—and the production's snap-snap timing fits this plot-driven, quirky comedy like constant name-dropping accessorizes a smooth pathological liar. That character would be Lee, who walks back into the life of childhood-friend Marjorie and her husband, a retired allergist who affords himself much respect in his medical world.

It's not clear at first how Lee, a born bamboozler from the get-go, will change the couple's lives, and I'm obviously not going to tell you here. But it's not altogether expected, and along with the laughs, Busch gives the play an underlying tension that Gaines' production nicely exploits.

Actress Marsha Mason is a perfectly confused and self-maligning Upper West Sider as the wife—she has a wonderfully expressive style—and David Garrison (TV's "Married With Children") winningly portrays her husband. Marilu Henner is the mysterious Lee, in the role she played on Broadway after she took over the character Michelle Lee had created in 2000. Henner, also a best-selling nonfiction author, is sleek and threateningly ebullient in the role—when she's on stage, you get the feeling a storm is brewing somewhere in the wings just waiting for her character to get back and control.

Ryan Shams plays a doorman who figures large by the end of the story, and the other character is Frieda, the self-appointed saintly Jewish mother of the allergist's wife. She's a great character, with many of the play's best punches, and actress Lynn Cohen took ill with laryngitis before the opening last week. When I saw the play, her replacement—Emily Jon Mitchell—had just come down from New York and script in hand, turned in an impressive performance that easily overwhelmed her status as a cast member in training.

In alerting the audience to Mitchell's last-minute appearance, Bucks County Playhouse's producing director Jed Bernstein announced before the play that in live theater, anything can happen. A great thing about the theater comes when the performers and the director manage to take anything that happens, and make it happen so well.

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"The Tale of the Allergist's Wife" runs through Sept. 1 at Bucks County Playhouse, 70 South Main St., New Hope. 215-862-2121 or www.bcptheater.org.