Credit: Carol Rosegg

The idea of a once very famous American Idol runner-up taking a role in an off-Broadway adaptation of a campy, low-budget, 1985 horror film about a grotesque New Jersey superhero sounds like something a humorist might dream up to illustrate the vicissitudes of the modern fame game. But The Toxic Avenger Musical is an actual show (playing at the New World Stages since April). And Diana DeGarmo, who placed second behind Fantasia Barrino in the third Idol season, is actually rather good in it.

Incredibly, TTAM is the third stage musical to be based on The Toxic Avenger, the Troma Entertainment-produced cult movie in which a wimp is transformed into a muscle-bound, but hideously deformed, righter-of-wrongs after falling into a vat of radioactive waste. This latest rock band-powered version boasts book and lyrics by Joe DiPietro (I Love You, You’re Perfect, Now Change) and music and lyrics by Bon Jovi keyboard player David Bryan. It also features around 10 million jokes at the expense of New Jersey, with the early couplet ”There is a place between heaven and hell/Don’t need a map, just follow the smell” offering a fair indication of what is to come.

Nick Cordero plays Melvin Ferd the Third, a weakling eco-warrior whose attempts to expose corruption in the fictional burg of Tromaville, N.J., land him face down in a barrel of radioactive goo. The busty DeGarmo is the object of Ferd’s affection, a blind librarian named Sarah who falls in love with the post-gooed-up Melvin and, at times, almost out of her skimpy wardrobe. The singer, who previously appeared in the Broadway version of Hairspray and joined Toxic Avenger last month, exudes an enthusiastic and essential gameness that was singularly lacking in fellow Idol-er Clay Aiken’s performance in Spamalot. Where Aiken retreated into the background, DeGarmo hurls herself unselfconsciously into the mayhemic proceedings as she duets with Cordero on the up-tempo ”Hot Toxic Love” or croons about her beau in ”My Big French Boyfriend.” (The sightless, and somewhat dim, Sarah believes her pungent new partner hails from the land of Belmondo and, more relevantly, brie.)

However, the star turn here is neither DeGarmo nor Cordero (though, to adapt the famous assessment of Ginger Rogers’ dancing talents, it can be said that Cordero does whatever DeGarmo does, but wearing fake muscles and an unpleasantly warm green mask). The real standout is Nancy Opel (Urinetown), who portrays both Melvin’s mother and the corrupt mayor of Tromaville. Opel gets the show’s best line when mom asks her mutated son, ”Do you want me to make you breakfast or are you just going to eat the dog?” But she really delivers as the lusty, machine gun-toting mayor, offering up a performance as entertainingly outsized as her character’s hair, which appears to have been knitted together out of at least three separate Faye Dunaway wigs. She also memorably essays both roles during the song ”Bitch/Slut/Liar/Whore,” a nice piece of stagecraft which self-mockingly points up the fact that the cast comprises just five actors (Demond Green and Jonathan Root do yeoman’s labor in a variety of smaller parts.)

The bad news? Like Evil Dead The Musical, which played the New World Stages a couple of years back, this is a show that never really transcends its shlock roots. The songs are sturdy rather than memorable and, while there may be no legal limit to the amount of jokes you can make about New Jersey, or blindness, you’re left with the thought that there probably should be. But if you are among the tens of millions of people who enjoy American Idol, campy horror movies, Bon Jovi, or drinking alcohol in your seat (something the New World Stages downright encourages) then Toxic Avenger is very far from being a poisonous night out. B