Generally speaking, playwrights shouldn’t have their past glories thrown in their face. The greatness of Tennessee Williams’s “Glass Menagerie” doesn’t make “The Rose Tattoo” a lesser play, even if it does suffer by comparison. Same with David Mamet’s “The Cryptogram” compared to “Glengarry Glen Ross.” So why should John Patrick Shanley’s superlative “Doubt” be held against him in the wake of a crushing disappointment like “Defiance”?

Well, because Mr. Shanley has all but demanded the comparison. He has announced that “Defiance” is a sequel (the second of a trilogy, to be precise) and given it another abstract one-word title beginning with “D.” More to the point, he has revisited the same central theme – personal responsibility in the face of potential wrongdoing within a strict chain of command – and hired the same crew, including director Doug Hughes, to put it together in the same theater.

And yet the finished product of this play is like a rough draft, a series of soon-to-be-discarded variations on a far more organized theme. This wheezing reiteration lives only within the shadow of “Doubt.”

“Defiance” may be set on a North Carolina military base in the waning months of Vietnam, but it unfolds with the clumsy plotting and prosaic dialogue of a World War II melodrama. Margaret Littlefield (Margaret Colin) provides exposition over the telephone (“Where are you? [pause] You’re still talking to the chaplain?”), then goes on to confront her tough-asnails husband, Lieutenant Colonel Littlefield (Stephen Lang), with comments such as “What about my service? When’s my turn?”

What is Mr. Shanley up to here? Has he temporarily forgotten his last name and confused himself with John Patrick, the author of dutiful midcentury war yarns like “The Hasty Heart” and “The Teahouse of the August Moon”?

What drama there is in “Defiance” comes largely from Chaplain White (Chris Bauer), an aphorism-prone preacher new to the ways of military life, and especially Captain Lee King (Chris Chalk), a virtuous young black officer who finds himself rising under Littlefield’s earnest but slightly patronizing tutelage. Several things fuel King, but ambition doesn’t seem to be one of them: He’s a sort of conscientious rejector, a man who grows increasingly un comfortable with the pressures of being a black man rising within a white power structure: “History doesn’t need anybody. I like that.”

Mr. Shanley has a handful of workable ideas here; unfortunately, he approaches each one like someone taking dissatisfied nibbles out of a half dozen chocolates. King’s ambivalence about his ascent, a hint of sexual tension between him and Margaret, the rekindling of his faith under White’s tutelage, parallels to various biblical tales (notably David and Bathsheba) – “Defiance” wanders toward each, only to lope backward into a sort of holding pattern.

This dramaturgical window shopping finally coalesces into a central conflict. But it takes almost an hour to get there, when a scene between King and a tremulous, hollowed-out private (played with memorable agony by Jeremy Strong) snaps Messrs. Shanley and Hughes to attention.

Sparks of the old Shanley vigor poke through here and in a few other places, as when King broaches the difficulties black soldiers faced in reconciling Martin Luther King’s ethos with their own military training. And several of the chaplain’s maxims have an unforced moral gravity: “Can’t face the demands of your own character … When a man runs from his own character, the world gets smaller and smaller. Like a pig chute at the slaughterhouse.”

But damning memories of “Doubt” float throughout even these stray moments. The chaplain’s admonition is really just a folksier (and flabbier) version of the self-righteous Sister Aloysius’s quote that “maybe we’re not supposed to sleep so well.”The increasingly disillusioned young captain has numerous parallels to the comparable naif in “Doubt,” and the ensuing battle over his allegiance also feels like a carryover. The earlier play’s propulsive, lean drama hasn’t been warmed over so much as diluted, with Littlefield first playing the role of the suspicious Sister Aloysius and then gravitating more into the morally suspect role of Father Flynn.

This is a tricky conversion, and it would be wonderful to say that Mr. Lang, a long-absent stage veteran in a part tailor-made for him, pulls it off. Alas, his interpretation loses much of its steely, crisp intelligence as the inevitable confrontation between Littlefield and King draws nearer. It is here that Messrs. Lang and Chalk, who is also solid for much of “Defi ance,” butt up against the same difficulties that poor Ms. Colin faced all along. Mr. Bauer fares best throughout, perhaps because his character exists largely outside the play’s tired domestic sphere.

Mr. Hughes’s forthright naturalistic style, usually so effective, makes for a surprisingly awkward fit with the play’s fussier elements. “Sometimes we know what’s right,” Chaplain White posits in one of his many adages, “but we haven’t the strength to wield the knowledge.”

Until April 30 (131 W. 55th Street, between Sixth and Seventh Avenues, 212-581-1212).