At the end, Next to Normal (2009) drew a thunderous ovation on its opening night Friday at the Media Theatre. But during the show, reaction was muted, because this innovative rock musical is so stunning that the audience did not know whether to applaud or cry.

In a notably chirpy and cheerful genre, how many musicals feature a star character who is mentally ill? Krissy Fraelich shines as the mercurial Diana, a woman with bipolar disorder. Full of humor, fear, and sorrow, her shifting, hallucinatory world transforms the lives of everyone around her.

Diana stirs up a batch of problems in long-suffering husband Dan (played by Barrymore winner Ben Dibble). Same for teenage daughter Natalie (Molly Sorensen) and her relationship with boyfriend Henry (Christopher Infantino). Diana's son Gabe (Ronnie Keller) plays a special role in the show's ingenious storytelling and dramatic irony.

Next to Normal is only the eighth musical to win the Pulitzer for best drama (Hamilton is the ninth). Tom Kitt (music) and Brian Yorkey (book/lyrics) also won the Tony for best musical score. Here, with help from the pop/rock orchestration of music director Ben Kapilow, brief speech slides gracefully into recitative, then bursts into song as the passion of the speaker rises.

With this cast, everyone in the family has a strong, clear voice. Sometimes, characters sing solo laments, as in "You Don't Know" (Diana) or "Growing Up Unstable" (Natalie). In other numbers they argue, with conflicting viewpoints meshing into perfect harmony.

The set design of Kyle Brylczyk is a broad, skeletal switchback of small platforms and white stairs. On the bare stage, it resembles a giant sculpture. You could call it "Unity and Dissolution," because in their choreographed comings and goings, that is how director Geoffrey Goldberg has desperate family members use it.

You know these folks are in trouble when two dedicated yet clueless psychiatrists, Dr. Fine and Dr. Madden (Patrick Ludt), are treated like family. Then again, so are you. Watching the show is intimate: You feel like a family friend, removed yet sympathetic to their struggles. Lighting designer Steven Spera uses sudden brightness to accent moments when the characters come face to face with reality.

That is especially true of Diana, who learns that discarding her grief is an unacceptable loss. Yet Diana speaks for all the family in her farewell song: "You don't have to be happy at all, to be happy you're alive." You are glad you met these people, proud of their authenticity and grateful to be cleansed of the mal foi tears of so many happy-ending musicals.