Imagine a rabbit hole, its entrance concealed, twisting down you don't know where. Imagine yourself following that hole into surreal adventures that parody the world above, as in "Alice in Wonderland." Or perhaps there are many holes, wormholes through timespace into parallel universes.

Both similes are suggested by "Rabbit Hole," David Lindsay-Abaire's sensitive, nuanced drama now at the Public Theater. But whatever adventure or disaster you might encounter down the rabbit hole, after many turns it could lead back to the world you know. You'd be in a different place, disoriented as your eyes met the light, perhaps enlightened but changed. That's like "Rabbit Hole," too.

Taking this journey down the topsy-turvy rabbit hole of grief are Becca and Howie, a nice couple in their 30s with a nice house (handsomely realized by Luke Hegel-Cantarella) in a nice, upscale New York suburb.

We meet Becca folding a large basket of children's clothes while talking with her younger, free-spirited sister, Izzy. Along with Becca's careful ritual of folding and stacking, we notice how compulsively neat she is. She instinctively tidies, pours purified water and bristles delicately at Izzy's offhandedness and at their blowsy, bull-in-the-china-shop mother, Nat.

Very gradually -- the playwright's delicacy of exposition is a marvel -- we learn that it's eight months since her and Howie's 4-year-old son, Danny, ran heedlessly into the street and was killed by a car.

Becca seems frozen; Howie wants life to continue. But they are equally consumed by the void: Becca retreats into Danny's room, framed above the stage like a chapel of grief, while Howie watches videotapes of him at play. In one of those we hear Danny pretending to be invisible. Gulp.

In his absence, Danny remains the biggest force in the room. And gradually we learn the situation is more complex. Becca is closed down, but Howie's loss runs deep, too, and expresses itself in surprising anger. They are marooned on separate emotional islands, too far apart for easy communication.

Their repression and unhappiness throw into comic relief the sister and mother. Garrulous Nat likes her wineglass full and talks about the Kennedys, cursed with the death of family members. Gulp again.

And again: Nat's son also died, though as an addict and at age 30, as Becca is quick to insist, rejecting any idea that her mother's loss and hers are similar. But of course they are. Nat says wisely that the anger never goes away, "which is fine, actually."

With a grief so large, everything relates to the force field of suffering. Narcissistic Izzy, who's neither married nor settled, announces she's pregnant, another painful looking glass for Becca's loss. And then Jason -- the teenager who drove the car that killed Danny -- shows up, leading to a confrontational Act 1 finale.

Although Act 2 begins with a tentative accommodation, grief continues its corrosive course. Becca is now taking a continuing-ed class, reading "Bleak House," and emotionally bleak this house is. In contrast, feckless Izzy and matter-of-fact Nat are welcome forces of unrepentant life. They start to pack up Danny's room (I heard sniffles around me) -- and then Jason reappears.

In a sense, little happens, but emotions surge out of sight. Lindsay-Abaire unpeels emotional layers, twisting and turning through the rabbit hole of grief. And then the characters emerge, different for the journey.

The ending may seem too upbeat to some, too uncertain to others. But it's the journey that matters. I was taken with the playwright's restraint. It's a play of small moments truthfully played, which suggests careful work by director Rob Ruggiero.

That restraint defines Erika Rolfsrud and Dylan Chalfy, emotionally truthful as Becca and Howie. Neither sensationalizes emotion, but it is there to intuit. Reactions will vary depending on the gender, age and parenting experience of the audience.

Jo Twiss' Nat and Joey Parsons' Izzy are more overt characters, appealing on their own but serving the play best as contrasts to the others' grief. Alec Silberblatt performs honorably as young Jason.

"Rabbit Hole" is a personal play, resisting noisy emotion or melodrama. Ultimately, I don't feel I know Becca and Howie as much as I would like. But perhaps as a result, I more easily imagine myself in their situation, renewing my sense of what I hold dear.