Amy Herzog's "4000 Miles" is based on a premise that at first glance seems too slight to sustain an audience's attention: A New Yorker in her early 90s opens her apartment door to an unexpected visitor, her twenty-something grandson, who moves in for a short while after facing tragedy on a cross-country journey by bicycle.

But the drama was a critical success during its two off-Broadway runs, winning an Obie in 2012 and receiving a Pulitzer nomination in 2013. The New York Times' Christopher Isherwood called it "altogether wonderful," and Time magazine dubbed it "the best play of the season, hands down."

Now Park Square Theatre is bringing it to St. Paul, featuring longtime Park Square actor/patron Linda Kelsey as Vera, the frail but feisty grandmother. Directed by another theater veteran, Gary Gisselman, it will be the second production in Park Square's new 200-seat space, the Andy Boss Thrust Stage.

Vera, who first appeared in an earlier play, "After the Revolution," is partly based on Herzog's own socialist grandmother, with whom she lived for a time.

"You've got an old leftie from the 1930s and '40s, the last of her group still living, and a young kid with liberal politics of a new age who doesn't want to eat bananas because of the jet fuel it takes to fly them here," Gisselman said. "His presence gives Vera a renewed sense of purpose, and also what might be the last close relationship of her life."

"4000 Miles" reunites Gisselman and Kelsey, who last worked together 43 years ago when both were just beginning their careers — a production of the French farce "A Flea in Her Ear" at the then-new Chanhassen Dinner Theatres.

Kelsey went on to a career in Hollywood, where she became best known for playing Billie Newman on the television show "Lou Grant," and Gisselman directed more than 200 stage productions, in the Twin Cities and Arizona.

Gisselman said the key to making a dialogue-dependent play like this work is "focusing on the tiniest details, and filling in memories and unanswered questions in your mind to flesh out the characters and their web of relationships."

Kelsey, who last appeared at Park Square just over a year ago as Mary Todd Lincoln in "Mary T. & Lizzie K.," was attracted to the play's frank, bold honesty.

"There is real love and respect between the two, real communication between the generations, but there's nothing cloying about it, nothing superficial or cute," she said. "It doesn't get all wrapped up in pretty bows and dance off into the sunset."

To help her fully inhabit the role, Kelsey consulted a gerontologist about what being a nonagenarian feels like.

"Amy has an unerring ear for dialogue that's truthful," she said. "The more we work on it, the more we're astonished at what it gives back, what we keep learning about these two, one at the end of her life, the other at the beginning of his."

She added, "The physical stuff is the easiest part. I walk slower and mind my balance, taking longer to get out of a chair. You've got to sort of wind yourself up and shove off.

"But she's dealing with a lot of inevitable loss. At that age, you've lost a lot of loved ones along with some of your abilities. The doctor told me there's a divergent path and people either age with grace and dignity or they get fed up, angry and can't manage it. Vera is walking that line, but she's not gonna give up."

The play's themes are especially poignant in a time when many grandparents and grandchildren in America never really get to know one another. Kelsey said working on it has made her think of her own two grandsons, one 3 and the other just 10 months old now.

"As little as they are, it's still such a powerful feeling," she said. "I hope if they came to me in crisis I could be there for them, and be as nonjudgmental and open as Vera turns out to be."

Kristin Tillotson • 612-673-7046