Amy Herzog, whose Belleville is a big Off-Broadway hit at the moment, is a rising star among young American playwrights. A Yale drama school classmate of Miami’s Tarell Alvin McCraney, Herzog began to soar with her 2010 play After the Revolution, then gathered more acclaim with 2011’s Obie Award-winning 4000 Miles.

South Florida first experienced Herzog’s work when the now-defunct Caldwell Theatre Company produced After the Revolution in 2011. Now GableStage is exploring more of Herzog’s funny, melancholy, truth-filled family drama in its new production of 4000 Miles.

The play takes a minor character from After the Revolution, the elderly Vera Joseph (Harriet Oser), and moves her center stage. Now 91 and dealing with the losses that come with advanced age -- bad hearing, forgetfulness, trouble finding words, death claiming friends and loved ones -- Vera is startled awake at 3 a.m. by an unexpected visitor.

Her 21-year-old grandson Leo (Michael Focas) has arrived at the door of her Greenwich Village apartment, the last stop on a cross-country bike trip marked by tragedy. Vera, the spirited widow of a man whose Marxist beliefs and activities got him blacklisted during the McCarthy era, is near the end of her life. Leo is merely at the end of a journey, driven in his 4,000-mile quest but otherwise aimless. He’d like to reconcile with his girlfriend Bec (Kate O’Phalen), who’s now a student in Manhattan, but she isn’t interested. So now what?

Herzog’s insightfully observed study of this familial odd couple is a journey too. The playwright examines how love binds people across generations, even as annoyance and flashes of anger infuse their daily coexistence. Herzog introduces unseen characters and plot points that she doesn’t always fully explain -- that’s a facet of her plays that can be frustrating -- but the world she creates in that Village apartment feels authentic.

Director Joseph Adler mines the script for its poignancy, conflict and, when Leo brings home art school student Amanda (Wei-Yi Lin) for a wild one-night stand, riotous comedy.

As the younger women in Leo’s world, O’Phalen and Lin create vastly different characters. O’Phalen’s Bec is angry, sour, finished with Leo if not quite over him. Because we grow to appreciate the amiable if flawed Leo, it’s tough to empathize with Bec. Lin’s drunk, style-conscious, unedited Amanda is a comedic tour de force, a woman dressed with singular style by costume designer Ellis Tillman. And when she’s startled by Vera’s sudden and inconvenient appearance, the moment is priceless. Amanda’s presence in 4000 Miles is fleeting, but once she exits, you miss her,

The heart of the play, though, is the deepening relationship between Vera and Leo. In designer Lyle Baskin’s just-right version of Vera’s rent-controlled home -- a tidy and spacious place, with an old-fashioned afghan on the back of the love seat and a photograph of Karl Marx on the wall -- a woman finishing out her life and a young man trying to get his started forge a deeper connection.

Oser’s Vera is lonely, frustrated by her physical losses and the infuriating neighbor who calls every night to make sure she hasn’t died. The actress is thoroughly convincing as a feisty leftist whose views on everything from politics to sex are as frankly expressed as ever. Vera is another great portrait in Oser’s impressive gallery.

As Leo, Focas communicates a lost young soul’s desire to hide from the rest of his family, grown-up responsibility and life’s pressures. His Leo is generally amiable, making his occasional eruptions of temper unnerving, and his yearning for Bec is palpable.

Herzog’s 4000 Miles is full of funny exchanges and painful ones, plot twists, awkward moments, exasperation and sweetness. Like life itself, it’s a journey of highs and lows, but at GableStage, it’s a ride worth taking.