Lord Edgar Vep of Mandacrest (Graham) has married Lady Enid (Merman) and spirited her away to his estate on the spooky English moors, where they're tended to by Jane the housemaid (also Graham) and a hunchback stableman named Nicodemus (also Merman). But there's a sinister oil portrait of the former lady of the house, Irma Vep (Merman again) over the fireplace, and a wolf — or is it a werewolf? — prowling outside in the fog. That's the plot, and that's all the actors need to keep the jokes coming at a machine-gun rate. The costumes (by Cecile Casey Covert) are so clever that the offstage changes are nearly instantaneous; Roberson, as the bald, one-legged hunchback, lopes offstage and reappears within seconds as the proper Victorian Lady Enid, looking like a Saints linebacker wearing a floral refrigerator cozy.
Graham and Roberson, who also co-directed the show, couldn't resist punching it up with a few New Orleans references (always a crowd hit in this town), and the mood lighting by Su Gonczy and many sound cues by Thad Griffin are a cinematic tour de force. James Jennings' drawing-room set (which is full of secrets) is a marvel of detail in a tiny space, and includes an oil portrait that actually drips blood. But the show belongs to Graham and Roberson's lunatic energy and sense of timing, and in Act 2, when Roberson takes on yet another persona as an Egyptian pyramid guide and enters the theater riding a camel (which spits water at the audience), it's clear that Irma Vep is no campy goof, but something vastly grander and more mad, where Shakespearean declamations give way to lowbrow jokes about cocks crowing in less time than it takes for these guys to take off a safari suit and slip into a Rose Parade-sized dress with matching wig.
The Mystery of Irma Vep
Le Chat Noir, 715 St. Charles Ave.
Fri.-Sat., 8 pm; Sun., 2 pm
Through Oct. 24