Brian Yorkey explains how his Pulitzer-winning Next to Normal evolved

Tom Kitt and Brian Yorkey's musical Next to Normal won the Pulitzer for its authors -- the book and lyrics are by Yorkey, the music by Kitt. Yet it began simply as an exercise for a musical theater workshop, one of those "show us everything you've learned in 10 minutes" assignments, Yorkey explained in an interview. He had seen a television report on shock therapy that indicated most patients were women and most of those prescribing the treatment men, and, "It hit me: What about a story about a woman who's suffered from mental illness her whole life and the men who tried to help her?" The result was a piece about a woman, Diana, suffering from bipolar disorder, and the effects of her illness on both herself and her family.

Other workshops and readings followed that first successful exercise, and after every one, audience members approached the authors to tell their own stories.

"It was really moving and humbling," says Yorkey, "a sign to us that it was something worth working on."

With each iteration, he explains, the protagonist became more fully realized, but she didn't come entirely to life until the casting of Alice Ripley, who starred off-Broadway in 2008, and on Broadway the following year, and who won a Tony for her performance. Ripley will be in Denver for the national tour.

The other characters, too, deepened over time. In the earlier versions, Diana's daughter, Natalie was constantly angry: "We realized she didn't have anywhere to go. She started angry and she ended angry. What was the journey?" Yorkey began examining the events of the play from Natalie's point of view as the younger sister, "trying not to make waves, trying to compensate for all the craziness at home by being as good as she can," and she evolved into a far richer character.

Through the long process of revision, the overall focus deepened, and the tone became more consistent. Songs were dropped, some replaced. Passages that had served more as the authors' commentary on medicine and American families and culture than as a means of moving the emotional action forward vanished. One number, for example, had Diana suffering a breakdown in Costco. "It was a great song, and Alice was brilliant doing it," Yorkey said, "but it was less personal, more about our idea of commercial culture. Now she has the breakdown at home in front of her husband and kids."

Over the last several years -- even as frivolous, content-free musicals continue to flourish -- audiences also have become used to darker, edgier work, and raucous, rock-inflected scores. "I'm interested to see what happens," Yorkey says. "As long as I've been aware of musicals -- which is a couple of decades now -- people have been saying musicals are dead and no one will ever work up to the level of the classics -- Steven Sondheim, Lerner and Lowe, Rogers and Hammerstein. That's a very high bar. No one's ever going to surpass the best of their work. All we can do is continue to write work that's honest and connects emotionally and intellectually with audiences. My Fair Lady and Gypsy are two of my favorite musicals. They're glorious. But why try to write them again?"

Presented by Denver Center Attractions, Next to Normal starts January 5 and runs through the 16th at the Ellie Caulkins Opera House. Tickets start at $20. Call 303-893-9582.

• Theater