In “Next to Normal,” a harried suburban mom is packing sandwiches for her family’s lunch. She puts slices of bread on the table assembly-line style, and when she runs out of space, she continues the manic process — on the floor.

This episode not only asks the nagging question of exactly how many family members exist in Tom Kitt and Brian Yorkey’s Pulitzer Prize-winning musical. It also raises the troubling red flag that this mother is scrambling to keep her home and heart from ripping apart at the seams. Diana’s dance with demons, and the toll it exacts on her husband and daughter, is the cord that runs through this musical treatise on the dual planes of bi-polar disorder.

As directed by Scott Schwartz at the Alliance Theatre, “Next to Normal” is an intense telling of an insanely good work of art that uses a lyrical and electric score to describe a tragedy of mental illness and its consequences. Even the best-adjusted psyches exist in fragile and precarious states of grace. But in the case of Diana (Catherine Porter) we get a queasily poignant account of a mind that perhaps has been short-circuited beyond repair.

There’s a bit of Hamlet and Gertrude (and Tennessee Williams’ Violet and Sebastian) in Diana and her son Gabe (Cary Tedder). The boy bleeds in and out of the picture — funnily enough — like some of the characters in Stephen King and John Mellencamp’s “Ghost Brothers of Darkland County,” only much more successfully. (After songs of wonder and despair, “I’m Alive” sounds almost creepy.)

It would be shoddy to give away much more than this, but the birthday scene is a tour de force, a dropped shoe of revelation, humiliation and keening sorrow.

For while Gabe is a very real spectre in Diana’s bell jar, her daughter Natalie (Lyndsay Ricketson) is borderline invisible. Even on a rare good day, Natalie, who is having an awkward romance with a stoner-geek named Henry (Jordan Craig), feels pretty beaten up by everything. Diana’s all-suffering husband (Bob Gaynor) is a victim, too.

Though the first act is nearly perfect, the second, which describes Diana’s downward spiral and endless treatment, is somewhat flawed by an excess of clinical drama and a rather unresolved ending. (Googie Uterhardt, by the way, plays Diana’s medical team.)

Storytelling quibbles aside, “Next to Normal” is superbly performed and choreographed (by Michael Jenkinson). Musical director Boko Suzuki’s band rips through Kitt’s score of sobering rock, classical riffs and even a bit of Jacques Brel (“I Dreamed a Dance”) to blistering and tender affect. Kevin Rigdon’s set — a doll-house structure that opens like a medicine cabinet and a trap door that requires some fancy ensemble footwork — is glorious. Mike Baldassari’s lighting is lovely and occasionally hallucinogenic. Sydney Roberts’ costumes are appropriate and, in the case of Henry, comical.

Anguish and grief tend to dim over time. What’s so devastating about Diana’s illness is the way it blazes on, eating down to the marrow of her soul.

Theater review

“Next to Normal”

Grade: A

7:30 p.m. Tuesdays-Thursdays. 8 p.m. Fridays-Saturdays. 2:30 p.m. Saturdays-Sundays. 7:30 p.m. Sundays. Through Nov. 11. $25-$65. Alliance Theatre, 1280 Peachtree St. N.E., Atlanta. 404-733-5000, alliancetheatre.org

Bottom line: Next to perfect.