An uncharacteristically small audience attended Saturday's performance of "Next to Normal" at Bloomington Civic Theatre. It seems that a rock musical about a suburban mom struggling with bipolar disorder is too edgy for the theater's core audience. That's a shame.

This Pulitzer Prize-winning show is challenging but deeply moving, and it's receiving a stellar production.

This is a depiction of the long and difficult process of the treatment of mental illness, the seductiveness and the danger of the disease. It's an indictment of modern pharmacology and the pain of being overmedicated. But there are no villains; the script treats all the participants with great compassion.

Director Joel Sass, making his Bloomington Civic debut, staged a nuanced production that is an emotionally accurate portrayal of the disease and its consequences, on the mother and on her family. Sass also serves as designer, and he created an attractive and efficient set, full of surprises: totally in sync with the show.

If the old theater adage is true that "directing is 90 percent casting," Sass has been especially successful. The strong six-member cast formed a real ensemble.

Karen Weber was first among equals as the mother, portraying the whole gamut of reactions to her illness, and its treatment, from confusion to pain to rage. She was particularly effective belting out the songs of her rage.

As the teenage daughter, Aly O'Keeffe captured the pain and anger of a spoiled childhood. As her goofy stoner boyfriend, Erin Patrick Miller added a nice bit of humor and heart to the proceedings.

Blake Rhiner made an especially strong impression, depicting the enigmatic character of the son.

As husband and father, Sean Dooley played a good man, struggling with what he cannot comprehend. He was stoic and solid, understated, and all the more effective because of that.

The through-composed score is excellent contemporary music, full of power ballads as well as complex ensembles. Music director Anita Ruth conducted an idiomatic performance. This music is very much in her wheelhouse.

This production earns the hope of its ending, even if that's a painful and ambivalent hope. It is one of the strongest and most emotionally affecting shows I've seen all year, and deserves to play to full houses.

William Randall Beard writes about music and theater.