The press script for Donald Margulies’s latest play, “Lunar Eclipse,” includes a prominent photo of the playwright’s late father-in-law, George Street, to whom the work is dedicated. Mr. Margulies eulogizes Street, who died in 2010, with two words: “Farmer. Beloved.”

One of the two characters in “Eclipse” is indeed named George, and is also a farmer, but for roughly the first half of this one-act piece, at least, he doesn’t come across as terribly lovable. Played in the show’s off-Broadway premiere by Reed Birney, a redoubtable stage and screen veteran who introduced the role in a Berkshire County production two years ago, George is a cranky septuagenarian who seems determined to defy and belittle his wife, Em, even as she showers him with care and affection.

The play opens with George sitting alone in a field, sobbing. When Em, played here by Lisa Emery, joins him to watch the lunar eclipse scheduled for that evening, his melancholy gives way to sour pique: After rejecting a blanket she offers to shield him from the cold night, he questions her interest in the event, or the land that has surrounded and sustained them through decades of marriage.

Em finally speaks up, asking her husband, “Could you possibly make my life sound any more trivial?” It’s at this point that “Eclipse” begins evolving into an actual conversation, in which we gradually learn the details of their relationship. Like those in many of Mr. Margulies’s plays, which include the Pulitzer Prize-winning “Dinner with Friends” and the semi-autobiographical “Brooklyn Boy,” these details are informed by loss and the challenges of self-discovery.

Here, unfortunately, both the characters’ struggles and their progress are charted in a manner that can seem predictable and prosaic. According to a publicist for the staging, “Eclipse” has been heavily revised since its last production, which I didn’t see, but whatever changes were made haven’t given the play a tremendous amount of depth.

Certainly, the trials that George and Em have endured during their decades together — notable among them raising a son with serious addiction issues — are made accessible, and engender sympathy. But the questions these characters come to ask themselves and each other, and the answers they produce, too often evoke the kind of banal philosophizing you’d expect from a not especially sophisticated TV movie.

At one point, Em attributes George’s grouchiness to the expectations placed on men of his generation: “You men’ll be boys in the schoolyard forever. Heaven forbid you show any vulnerability whatsoever.” Many of the couple’s exchanges evolve from this same trope, of the loving wife trying to goad her husband into expressing his feelings more openly.

Under Kate Whoriskey’s meticulous direction, though, “Eclipse” succeeds as a showcase for its two gifted, game players. Mr. Birney, whose effortless emotional transparency has impressed in a wide range of roles, manages to lend grit and poignance to dialogue that can border on boilerplate, so that George seems as fully, frustratingly human to the audience as he does to his wife.

Ms. Emery, who was delicious in a far more sinister role in the Netlflix series “Ozark,” proves equally adroit at fleshing out Em, so that we see both the character’s warmth and her spine from the beginning. When George fears their daughter will sell the farm after they die, Em reassures him: “It’s greedy of us to think what we leave behind is something so special that needs to go on.”

Em adds, “We all do the best we can do while we’re here and then, time to move on and make way for the next squatter.” Like much of the advice proffered in “Lunar Eclipse,” it’s pretty obvious, but at least it’s served here with grace and heart.