Park Square Theatre's production of "4000 Miles" opens in ominous confusion. An elderly woman in a nightgown confronts a gawky, disheveled young man who had entered her darkened apartment. She's verbally incomprehensible because she doesn't have her dentures in and mentally discombobulated because it's 3 in the morning. He's impatient, spitting out hectoring, disjointed statements.

It only becomes apparent after several minutes that what we're witnessing isn't a late-night home invasion but rather a reunion between grandson and grandmother.

Grandson Leo wheels a bicycle onstage in that first scene and the title of Amy Herzog's play refers literally to the distance he's traveled to arrive at his grandmother Vera's New York apartment. But in a larger sense, it delineates the distance that can exist between generations and families. Over the course of 100 minutes these two people ultimately bridge that distance as they negotiate their complex and often prickly relationship.

Linda Kelsey offers up an impressively layered and meticulous performance as Vera. This isn't your stereotypical cookie-baking grandma. A self-avowed "lefty," she's an idiosyncratic and salty firebrand, impatient, critical and unconventional. For all her seemingly youthful outlook, however, she's also clearly feeling her age as she moves carefully, strains to hear conversations and struggles to find words. Plays that give such centrality to older female characters are still rare and it's a pleasure to see how much Kelsey wrests from this meaty role.

Gabriel Murphy is equally sure in his portrayal of Leo, with the hunched posture and defensive attitude of a young man straddling the uneasy divide between adolescence and adulthood. Over the course of a series of short scenes that span three weeks, Leo and Vera spar, snap at and warily circle each other as their relationship deepens and a secret that has lurked throughout is finally revealed.

Two other characters — Leo's former girlfriend Bec, played by Becca Hart, and another girl that he spends one drunken evening with (Joann Oudekerk) — are well-acted, but suffer from seeming almost too peripheral to the central action between Leo and Vera.

This is Park Square's second production on their new Boss Stage and adjustments are still being made to fine tune the space, but it offers a nice setting for this intimate and often raw drama. Director Gary Gisselman uses the space effectively to keep the action focused. Rick Polenek's set gives the play a strong sense of place, which is complemented by C. Andrew Mayer's sound design conjuring the ambient noise of the surrounding city.

Park Square deserves much credit for such a competently staged, well-acted and often moving production.

Lisa Brock writes about theater.