Insurgo Theater Movement's "Cannibal! The Musical!" gets right to the point. A few people wander onto the stage and immediately get their limbs torn off and eaten, complete with spurts of blood so voluminous that audience members in the first couple of rows share in the bounty. It must warm the hearts of die-hard theater lovers to see how the musical has changed since the days of Gilbert and Sullivan.

What is genuinely surprising, though, is how much mileage John Beane's adaptation of Trey Parker's 1996 screenplay gets out of a one-note joke.

Parker's spoof of the wholesomeness of the movie musical was disappointingly lame. You expected more outrageousness from the co-creator of "South Park." But Beane not only adds layers of comedy, he transforms the movie into an homage of stage convention. The improvisatory quality of the dialogue, the joking about a quick costume change, the chase sequences (featuring an unexplained alien) that have a heavy actor walk around a saloon entrance set piece because he's too fat to walk through, a horse that is now a galloping, beautiful woman, all feel born of the stage.

The story tells the tale of Alfred Packer (Shawn Hackler), a man accused of eating his scouting party on a late-1800s expedition to the Colorado Territory. But it's just an excuse for some tongue-in-cheek show-biz-y songs, and some cleverly awful Mel Brooks-type jokes.