Chad Wheeler and Kari Ginsburg in ”Next to Normal” from The Keegan Theatre. (C. Stanley Photography/ )

“Do I really live here?” the fragile suburban resident Diana wonders as she arrives home from a bout of electroconvulsive therapy in the musical “Next to Normal.” Her husband and teenage daughter try to jump-start her memory. Doesn’t she remember the dogwood blooms? Last Christmas? The day when her daughter, as a baby, took her first step?

Diana draws a blank: To her, the house is alien territory. Fortunately, by this early Act II number in Keegan Theatre’s “Next to Normal,” directed by Mark A. Rhea and Colin Smith, the performers have demonstrated that they are, more or less, at home with the material. Although the cast’s portrait of a struggling family feels hesitant and inauthentic early on in the show, and while the odd vocal line throughout occasionally lacks assurance, the production is overall an effective showcase for this hugely affecting rock musical.

Scored by Tom Kitt, with a book and lyrics by Brian Yorkey, the Pulitzer Prize-winning “Next to Normal” depicts a household coping with mental illness. Diana (Kari Ginsburg) has lived for years with bipolar disorder, which has resisted the ministrations of multiple doctors (Scott Ward Abernethy) and nearly exhausted her loyal husband, Dan (Chad Wheeler). As Diana’s health deteriorates, and her insecure daughter Natalie (Caroline Dubberly) tries to dull her own pain with drugs, it becomes questionable whether the family will survive.

The scenario’s suspense and emotion would be stronger if this cast displayed more plausible family chemistry in the show’s early sequences: At times, you get the sense that the characters — who include Dan and Diana’s son Gabe (David Landstrom) — are more acquaintances than kin. It doesn’t help that Ginsburg hardly looks old enough to be the parent of a seasoned, sullen high-schooler like Dubberly’s Natalie.

But the actors warm to their roles and relationships as the well-paced production continues. Wheeler invests Dan with touchingly weathered melancholy, and Ginsburg aptly suggests Diana’s vulnerability and disorientation. Christian Montgomery turns in a disarming portrait of Henry, Natalie’s stoner boyfriend; and Abernethy makes good use of understatement while conveying the doctors’ compassionate professionalism. Dubberly and Wheeler are the production’s strongest singers. (Music director Jake Null conducts the mostly fine-sounding band.)

The show is well served by Matthew Keenan’s set, whose stylized touches — fractured doors, a near-bewildering number of staircases, a suspended starburst that resembles a shattered plate — speak of the household’s sustained distress. The environment nicely showcases the production’s most-memorable moments, which include Diana’s flaring of frustration in the number “You Don’t Know” (enriched by deliberately manic lighting, designed by Allan Sean Weeks), and the funny sequence in which Dr. Madden — as seen by the hallucinating Diana — morphs repeatedly into a shrieking rock star.

Quieter but just as compelling is the poignant “Song of Forgetting,” which follows Diana’s ECT treatment. At aching moments like this one, some opening-night theatergoers could be heard crying.

“Next to Normal,” music by Tom Kitt, book and lyrics by Brian Yorkey. Directed by Mark A. Rhea and Colin Smith; costume design, Alison Johnson; sound, Rachel Barlaam; projections, G. Ryan Smith; properties, Carol H. Baker; hair and makeup, Craig Miller; choreography, Kurt Boehm. About 2 hours and 30 minutes. Tickets: $45-55. Through July 10 at the Andrew Keegan Theatre, 1742 Church St. NW. Call 202-265-3767 or visit keegantheatre.com.