How many times has a movie or play lost you at the ending? Everything is chugging along just fine, and then the director cops out and squanders all the good will built up along the way. You probably left with an unfavorable impression of the piece, even if you liked pretty much everything that led up to those last few minutes.

By that logic, Rinne Groff’s “The Ruby Sunrise” should generate great word of mouth. It takes a long time, but the play eventually doubles back – turning two underwhelming plot threads into a knockout of an ending. Oskar Eustis, making his directorial debut as the Public Theater’s new artistic head, and Ms. Groff filter two time periods through a visually sumptuous, satisfyingly Pirandellian blend of stagecraft and psychological savvy. But that blend of insight and innovation is in awfully short supply for the first two hours.

Much of Act I is devoted to the tale of scrappy young Ruby (Marin Ireland), who arrives in 1927 Indianapolis with highfalutin talk about making a radio that can show pictures as well as sounds. She’s even got a name for it: television. Henry (Patch Darragh), an apple-cheeked student, steals lenses and such for her invention but would rather steal her heart.”How can she be my girl when all she wants me to do is stick wires everyplace?” he complains to Ruby’s salt-of-the-earth Aunt Lois (Anne Scurria). Plucky Ruby sticks to her guns – “Nobody believed Marconi either” – but is she too late? And what will become of her unborn baby?

If the dialogue thus far has been a bit prosaic, a bit thick on the tongue, Ms. Groff has her reasons. Suddenly, with a flash of klieg lights, she whirls us from sleepy Indiana to bustling Manhattan circa 1952. (Deb Sullivan’s dynamic lighting is flashy when it needs to be.) We are in the world of live television plays, where cigar-chomping studio heads placate the looming censors, and the Paddy Chayefskys of the world labor to get meaningful stories on the air.

One such story comes from Lulu (Maggie Siff), a bright young “script girl” from Indiana who wants the story of her mother to reach all across America. It’s a story about a young woman who went to Indianapolis in 1927 to invent television. But Lulu’s goals prove as difficult to achieve as her mother’s: This is the 1950s, and Ruby’s dreams of uniting the world’s “comrades” through television make the studio nervous. Not to mention that the ramifications of Ruby’s choices in real life (or what passes for real life in “The Ruby Sunrise”) make Lulu nervous.

Unfortunately, Ms. Groff’s smartmouthed New Yawkers are no more persuasive-sounding than her cornpone Midwesterners. The writing here is so arch, so scripted, that one almost expects to see the curtain pulled back on yet another layer: We’re actually watching a modern-day docudrama about a 1950s movie of a 1920s story, or something like that.

Of course, when a playwright known for structure-tweaking works like “The Five Hysterical Girls Theorem” starts a play with the line “It happened just like this,” the audience’s antennae should go up a bit. Ms. Groff is playing with layers of fiction, reality, narrative, and subjectivity – all fine and good, except that intentional artifice still feels artificial.

Ms. Scurria, a carryover from regional productions of “Ruby,” is superb as both Aunt Lois and the hard-bitten Broadway baby who later plays her. And Jason Butler Harner gives a wickedly charming performance as the morally compromised screenwriter whose weaknesses fuel much of the Act II drama. He shares the play’s sharpest dramatic writing in an icy exchange between Tad and Elizabeth Hunter (Ms. Ireland, even better here than as Ruby), the blacklisted actress originally slated to star as Ruby.

By the time the lovers’ tiffs and their various obstacles are addressed, it’s time to see Ruby’s tale unfold, “live,” on stage and on screen.This is where all the play’s themes finally come into stride. Mr. Eustis clearly enjoys replicating the scrappy, low-tech techniques of live television, as spray bottles simulate rainfall and scurrying stagehands move scenery just out of camera range. Ms. Groff’s dialogue hums with a new polish, and the performances are great – even the bimbo who replaced Elizabeth Hunter is pretty good. 1952 reality, 1952 fiction, 1927 fiction, and something close to 1927 reality resonate over one another with invigorating wit and poignancy.

It’s an entertaining, thought-provoking commentary on the transformative (for better and for worse) powers of storytelling. Audiences crave that kind of ending, so much so that some may be willing to forgive the two hours of pedestrian dialogue and obvious confrontations that led up to it. But that’s asking a lot.

Until December 18 (425 Lafayette Street, 212-260-2400).