A comic-book writer by day, Roberto Aguirre-Sacasa has quickly built a reputation for writing what Hollywood calls “genre” plays, devoted to horror, science fiction, and other disreputable subjects. His maniacally chatty new comedy, “Based on a Totally True Story,” by comparison, lopes breezily down an extremely mainstream path: Naif gets his head turned by success and abandons those around him before finally seeing the light.

But Mr. Aguirre-Sacasa and his resourceful director, Michael Bush, have given robust life to this wisp of an idea, stuffing it with great clothes and dropped names and disappointing dads and even a happy ending. They get ample help throughout from a cast led by Carson Elrod as Ethan Keene, an endearing, corruptible, motor-mouthed, mostly totally autobiographical playwright/comic book artist/would-be screenwriter, and the priceless Kristine Nielsen as Mary Ellen Eustice, the producer who sinks her claws into his script.

Ethan’s favorite superhero growing up was the Flash, largely because the guy moved so fast that he could be in two places at once. And Ethan’s relentless patter comes frighteningly close to launching him into a comparable state of liftoff. He confides in the audience about everything from his pajamas to his long-suffering boyfriend (a charming Pedro Pascal) to his preferred writing location: “The Starbucks (I know) in the Barnes & Noble (I know) at Broadway and 66th Street, because of that row of picture windows that look out over Lincoln Center (I know).”

Of course, acknowledging cliches don’t make them any less cliched. And we are dealing here with a sensitive young New Yorker (I know) who keeps finding himself ditching his “serious” work for the mammon of Hollywood (I know), even if that means (I know) compromising his efforts to appease the suits. That’s right: Mr. Aguirre-Sacasa has gone out on a limb and created an unsympathetic Hollywood player.

Mary Ellen Eustice is a character familiar from “The Little Dog Laughed,” “The Dying Gaul,” “Speed-the-Plow,” and a dozen other plays – the wise and withering mini-mogul dedicated to corrupting the youthful scruples of those naive (usually gay) New Yorkers. She is slightly snugglier than these other barracudas, occasionally taking the time to counsel Ethan on his more questionable personal decisions. As she tells him, “That’s living, my young screenwriter. Accumulating regret.” But if she thinks his brooding, allegorical thriller would benefit from a deadly jellyfish attack, guess what’s going into the script?

(Perhaps the most bizarre thing about “Totally True Story,” incidentally, is that it’s the second off-Broadway play in less than a week to use killer jellyfish as a major plot point, following Marga Gomez’s “Los Big Names.”)

Ms. Nielsen’s wild-eyed, tremulous, bouncing-off-the-script style has en livened any number of recent plays, particularly those of Christopher Durang, but Mr. Bush reins her in somewhat here. She still throws her eyes, hands, and posture into nearly every line – many of the Mary Ellen-Ethan conversations take place over the phone, allowing her a broad array of unseen (by Ethan) reactions – but Ms. Nielsen remains content this time to ride the material instead of wrestling it to the ground.

Mary Ellen is actually more likable than Ethan at times. Mr. Aguirre-Sacasa has a firm sense of the circuitous illogic that even a fairly self-aware person can end up applying as he compounds one bad decision with another. By the end of Act I, our protagonist has compromised nearly everything he holds sacred about his screenplay, while somehow finding time to ignore his boyfriend and yell at his dad. And yet we still like the guy, thanks in no small part to Mr. Elrod’s ebullient, crafty performance.

Not even Mr. Bush’s crisp direction and Linda Cho’s hipster-chic costumes can cover up some of the play’s gaps and dead ends. A subplot about Ethan’s mild-mannered father (Michael Tucker, who cuts a sympathetic figure despite an odd pan-mid-Atlantic accent) and his marital woes never really takes off: Mr. Aguirre-Sacasa’s focus is too inward to make sense of this combustible new ingredient. The whimsy is occasionally troweled on, carrying through to the very last line. And while Erik Heger makes a commanding New York debut in a handful of supporting roles, too many of these parts are just too schematic to warrant the time they’re given.

“Schematic,” as it happens, is a quality that Ethan hopes to avoid in his screenplay – a desire that horrifies Mary Ellen. “There’s no such thing!” she gasps when he asks if it’s too schematic. (And when Ms. Nielsen gasps, one fears both for her esophagus and for the entire theater’s oxygen supply.) “There’s too challenging and too original, but never too schematic!”

Audiences will find “Based on a Totally True Story” about as challenging as the Flash would find a 5K fun run. But the Mary Ellens of the world have a point: Not being challenged isn’t always such a bad thing. Being entertained and maybe even moved a little can be totally sufficient.

Until May 28 (131 W. 55th Street, between Sixth and Seventh Avenues, 212-581-1212).