Florence Lacey in “Kaleidoscope,” a new musical from Matt Conner and Stephen Gregory Smith. (Keith Waters)

Broadway veteran Florence Lacey is cracking up compellingly in the new dementia musical “Kaleidoscope,” getting its premiere from the useful Creative Cauldron in Falls Church. Lacey, who was Signature Theatre’s Norma Desmond in “Sunset Boulevard” and who has played the lead in “Evita” thousands of times, portrays a star losing her mind even as she barnstorms the country in her one-person stage memoir. Her depiction of accelerating mental erosion is as exquisitely measured as her silvery singing.

The musical is another Creative Cauldron project from Signature veterans Matt Conner (music, lyrics, direction) and Stephen Gregory Smith (book, lyrics, direction), and its simple approach is moving and graceful. Lacey enters the intimate, lab-size space with a peppy tune as Evelyn Thorne, a clearly polished performer whose showbiz history is being trotted out for the road.

After all, the show is never over, as her daughters say — though why does Evelyn insist they call her “Miss Thorne”? Roles are fluid, and in question: Susan Derry plays Evelyn’s director and/or her daughter, just as Catherine Purcell is sort of a stage manager-daughter. The muddle is deliberate, and the understated emotion that plays out on all three of the performers’ faces often ripples with helplessness.

The songs nearly overwork showbiz conceits as Evelyn sings such lines as the bright “Find your light” early and the dusky “curtain coming down” late, but Conner and Smith mainly succeed in keeping their touch light and honest. The framework of Evelyn’s solo show sets up some agonizing forgetting and painful family revelations that hit sharply with Evelyn’s refrain of “mother stayed at home,” repeated obsessively and with a punchy twist.

A dark ironic seam is mined, too, with Evelyn scattering rose petals in a parody of glory. This kind of grim inversion could slouch toward camp, but the show stays human-scaled: It never tries to exploit dementia or sensationalize disorientation. Studio Theatre’s current staging of the similarly themed drama “The Father,” on the other hand, bombards the audience with concussive transitions — repeated blasts of sound and in-your-face light that are less of a jolt into the character’s experience than a shock nearly out of the play altogether.

Losing my mind: Florence Lacey in “Kaleidoscope.” (Keith Waters)

Like “The Father,” “Kaleidoscope” doesn’t have a lot fresh to say about the sad dynamics it aptly depicts, nor does it have the snappy plot hook of “Proof,” David Auburn’s 2001 Pulitzer winner on mental illness now being revived at the Olney Theatre Center. The “Kaleidoscope” cast’s fourth member is young Sophia Manicone, and the looks Lacey’s Evelyn gives this figure are among the most paralyzed of the night. Lacey seems to know the psychological terrain, and — much like Ted van Griethuysen, who is intimidatingly crisp, then woozy, and unpredictably passive-aggressive in “The Father” — she lashes and recoils convincingly.

Conner’s music has a romantic strain limned with melancholy; waltzes surge and evolve, with an especially lovely yet tense number for all four women (all fine singers) late in the show. The score is well played by a piano-violin-reeds trio, and although Conner and Smith may continue to revise aspects of this piece, you wouldn’t want to hear the arrangements boosted much. The show’s delicacy, in the score and in Lacey’s perceptive performance, is an asset.

Kaleidoscope, music and lyrics by Matt Conner, book and lyrics by Stephen Gregory Smith. Directed by Matt Conner and Stephen Gregory Smith. Scenic design, Margie Jervis; costumes, Alison Samantha Johnson; lights, Lynn Joslin. About 70 minutes. Through May 28 at Creative Cauldron, 410 S. Maple Ave., Falls Church. Tickets: $30. Call 703-436-9948 or visit creativecauldron.org.