2004’s The Old Masters, one of the final works of the fecund British playwright, screenwriter, novelist, and memoirist Simon Gray, is a largely fact-based account of a fight over the attribution of a 500-year-old painting, and for most of its meandering first act, it’s exactly as dry and academic as that unpromising logline would suggest. It picks up in the back half, though, with the arrival of red-raced, stentorian-voiced Conrad Feininger as Joseph Duveen, a terminally ill art dealer on a mission. He’s determined to persuade his longtime frenemy, the art historian Bernard Berenson (“BB”), to certify the painting as that of the Renaissance master Giorgione, who died young and left behind few works that can be authenticated with certitude, rather than that of Titian, one of Giorgione’s more prolific apprentices. Berenson’s verdict is likely to influence the painting’s sale price by what under different circumstances might be thought of as a life-changing sum.

You can’t take it with you, alas. Duveen gives Berenson his word he’ll be dead within three months, and anyway it’s 1937 and “the duck”—Mussolini—is ramping up his war machine. The play eventually coalesces into a study in integrity, or stubbornness, with Berenson refusing to be swayed in his opinion of the painting’s likely authorship even though he could profit enormously by doing so.

For too long, this battle of wills is a one-sided one. Berenson, given a believable shading of vanity and vulnerability by David Bryan Jackson, spends the diffuse first act sulking about his lavish villa outside Florence (tastefully rendered by set designer Carl F. Gudenius), complaining to both his sickly wife and his housekeeper/mistress about his diminished fortunes and the likelihood of war. It’s a relief when Feininger’s Duveen finally shows up to try to—in the most civilized and diplomatic terms possible—bribe him. Indeed, the way Feininger and Jackson snack on the decorous language of their quarrel is the play’s most attractive feature, because the questions of authenticity and perceived versus innate value it poses, while interesting and insoluble, have been contemplated with greater style and insight elsewhere. And also, arguably, here, at Washington Stage Guild, in Inventing Van Gogh just two months ago. (Van Gogh’s director, Stephen Carpenter, appears onstage in The Old Masters as Duveen’s fastidious secretary.)

The Old Masters becomes more compelling, perhaps, should you choose to factor in its local resonance. “The Adoration of the Shepherds,” the painting whose provenance is here debated, hangs in the National Gallery of Art, where its accompanying text indicates it is “now almost unanimously accepted” as having been painted by Giorgione. It was put there not by Andrew Mellon, the museum’s primary donor and founder, but by Samuel Kress, a collector who made his fortune through five-and-dime stores, and who for this reason, apparently, is the object of much derision in The Old Masters. Duveen had hoped to sell “The Adoration of the Shepherds” to Mellon as a Giorgione, at a Giorgione price. Its contested authorship, the play suggests, resulted in the Kress Foundation buying the painting, presumably for less than Mellon would’ve paid. It donated the painting to the NGA the following year, in 1939.

I doubt that very many of the people who’ve viewed the painting in the gallery for the price of $0.00 during the last seven decades care which rich person was the last to own it or at what price, nor should they. It is the very definition of a MacGuffin, albeit an unusually beautiful one. It has inspired a well-spoken, well-acted play that you wish would come to the point more quickly than it does.