Long Wharf Theatre’s latest show is a grab bag of kooky delights. “The Mystery of Irma Vep,” a campy “penny dreadful” by Charles Ludlam, evokes a murder mystery mood with a Mel Brooks flavor.

If “Irma Vep” were a casserole, the recipe would call for one part cross-dressing, a liberal dose of allusions to cultural classics from “Wuthering Heights” to “Nosferatu,” and a sprinkling of “Rocky Horror Picture Show”-style audience participation. The cooking process would be something like an intermittent thrust into the fire that reflects the frenzy of activity required of the two actors (Jeffrey T. Roberson and James Lecesne) who, between them, play two female and five male characters. In fact, the two actors are billed in the program both as themselves and as their transvestite alter-egos: Lecesne and Roberson have bios in the production’s program for their “female” counterparts, Jocelyn Burnet-Phipps and Varla Jean Merman respectively.

The show’s plot is serious enough. The story takes place on Mandacrest estate, where it is constantly dark and the inhabitants are filled with concomitant angst. We are told by the estate’s owner, Lord Edgar (Lecesne), that the house is beset with constant howling winds and gloomy darkness, like those that characterized the tempestuous manor in “Wuthering Heights.”

Edgar’s lover, Lady Enid (Roberson), does not meet the standards of Edgar’s loyal maid, Jane (Lecesne/Burnet-Phipps), because the latter still feels affection for the last mistress, the late Irma Vep. Irma’s massive picture hangs over the fireplace and even appears to ooze blood twice during the play, representing both her haunting impact on the characters and Enid and Edgar’s harsh dishonor to her memory.

Accessory characters who change into werewolves at midnight, kidnapping plots, decades-old murder conspiracies and spur-of-the- moment pilgrimages to pharaohs’ tombs enter the plot in the second half of the play, but saturate it to the point of endangering the play’s credibility.

Nonetheless, Ludlam’s signature “theater of the ridiculous” makes up in delirious humor what the play lacks in believability.

The hysterical silliness of “Irma Vep” depends largely upon frequent quick changes — and not just quick changes, but near-instantaneous ones. Every few minutes, one of the actors is called by some on-stage development to go summon another character who is also played by him. Frequently, these characters are not of the same gender, necessitating challenging transformations.

In one such change, Lecesne/Burnet-Phipps morphs from maidservant Jane to master of the house Lord Edgar in under 10 seconds of what must be sheer frenzy offstage. Lecesne/Burnet-Phipps exits as the pooh-poohing housekeeper, clad in a stifling black Morticia Addams dress, “her” hair plastered into a face-lift up-do. Shortly thereafter, Lecesne emerges as Lord Edgar in a flurry of importance with a variation on the costume that suggests the character’s recent hunting excursion. With a bit of careful (and very controlled) mussing, Lecesne’s wig comes to resemble the fashionably styled male long hair popularized by George Washington.

But while watching Lecesne/Burnet-Phipps’ Jane is quite amusing, it’s Roberson/Merman’s take on Lady Enid that inspires sheer delight. Enid, as played by the taller-than-average (by both female and male standards) Roberson/Merman, towers over Lecesne’s Edgar as the characters hold each other tenderly. Enid’s falsetto is so shamelessly bad it seems if the pitch were to get any higher only dogs would be able to hear it.

While the script is cheesier than Wisconsin — complete with calls for a “Cairo-practor” during a brief (and apparently muscle-sore-inducing) stint at the Egyptian pyramids — the absurdity is all part of an intentionally outlandish experience. The actors’ sheer enthusiasm mitigates the hokey feel of some scenes in the production. Each actors’ complete immersion, not only into each character but also into each required gender, is what makes the play a standout.