“Color and light,” as one number in Sunday in the ParkWith George puts it in deliciously staccato rhythms, are what the post-impressionist painter Georges Seurat was obsessed with manipulating—so the muted grayscale expanse of Daniel Conway’s handsome set may surprise audiences filtering into the Signature Theatre.

Fear not: Color and light will flood the space soon enough, as director Matthew Gardiner and his assembled forces put together a deeply felt portrait of an artist struggling to connect the dots of life and work. When theater fans point to Signature as a company with a knack for Sondheim, this kind of immensely assured, emotionally transparent production is what they’re talking about.

It’s 19th-century Paris—at least in Act 1, but more about that later—and the locals are taking in the Sunday-afternoon air on the island of La Grande Jatte. Among them, but not of them, sits the intense, dark-haired George (no “s” in Sondheim and James Lapine’s telling), a painter working up a sketch of a comely young model, Dot, who’s also his lover, and who’s more than a little impatient with George’s intense focus on his art. “Artists are bizarre. Fixed. Cold,” she grumbles in the brisk, angular title number, and as far as George is concerned, she’s not wrong.

That impatience, and George’s own frustration with Dot’s inability to grasp how urgently the creative impulse has seized him, will drive a wedge between them. And though this heady musical is less concerned with interpersonal drama than with the struggles of an artist intent on realizing a fresh vision of his world, Claybourne Elder’s intense, aloof George and Brynne O’Malley’s appealingly pert Dot make for a couple whose demise is worth mourning.

In fact, that sense of real relationships, real emotional stakes, is one of the strong points of Gardiner’s staging, along with richly confident vocals across the board and the seamless, well-rounded sound of Jon Kalbfleisch’s 11-piece orchestra. (“Sunday,” the slow-building chorale that closes Act 1 as Seurat’s masterpiece comes together in three dimensions on stage, has never sounded better.) And once the action has leapt the Atlantic and a century ahead in Act 2, the relationships between one artist and his descendant, one style of work and another, one artistic community’s dynamics and that of a later one’s, are teased out and illuminated subtly and intelligently.

Act 2 concerns itself with another George (Elder again), whose family tradition holds that he’s descended from the other, and his grandmother Marie (O’Malley), the 98-year-old daughter of Dot. Where the Parisian painter struggled to gain an audience and reputation in his short lifetime, this young light sculptor is a bona fide success, with a new museum commission to display. Where the George of “La Grande Jatte” never sold a painting, the George of what’s presumably the Art Institute of Chicago is an old pro at glad-handing critics, patrons, and museum bigwigs.

But where the 19th-century George never wavered in pursuit of his vision of an intricate new way of composing images, 1984 George suspects he’s running out of ideas—and it’s in those two takes on the artistic impulse that the show’s two very different acts begin to chime together. The feisty Marie provides a connecting thread (and some wry comic relief), and in a final-scene communion with the spirit of the long-deceased Dot, George is able at last to learn what she knew: that obsessing about the future or worrying over the past won’t get the art made. “Move on,” she urges him in the show’s most passionate duet—its passion rooted not in romance, but in the desire to create—and he picks up the refrain, their voices blending over a swelling orchestra until color and light and care and feeling are one glorious wash of sound. (Many a sniffle was heard in its wake on press night, let me assure you.)

And then the characters in that painting begin to reassemble—anonymous on Seurat’s canvas, but given vivid life in Sunday in the Park by Lapine and Sondheim, and by Gardiner’s tight-knit ensemble cast. Donna Migliaccio’s Old Lady, alternately waspish and warm; Valerie Leonard’s artist’s-wife Yvonne, both snobbish and insecure; Paul Scanlan’s gruff Boatman and the giddy Celestes of Susan Derry and Erin Driscoll; and more, all of them contributing to a very fine picture of what it means to pour your soul into something, and what it might feel like to become immortal as a result.

4200 Campbell Ave., Arlington. $40-$104. signature-theatre.org. (703) 820-9771.