So has Second Stage been advertising its current attraction with a banner that screams “From the co-author of Thoroughly Modern Millie!”?

No, and that’s to the theater’s immense credit. Although getting a tie-in with a Tony-winning musical makes sound business sense, the powers-that-be on West 43rd Street know that the 2002 hit tuner and this prison drama have precious little in common. Yes, Dick Scanlan’s name is on both shows, but Whorl Inside a Loop has much more on its mind than worrying if a secretary can find a way to marry her handsome and rich boss.

However, Second Stage’s ads for Whorl Inside a Loop have stressed that the show is “From the team that brought you Everyday Rapture.” Indeed, Scanlan, actress Sherie Rene Scott and director Michael Mayer collaborated on that revue five years ago. It turned out so splendidly that they decided to do another show.

It would, though, be one in which there would seem to be very little “rapture” – at least as defined by the dictionary. How can there be “intense pleasure and joy” inside the walls of a prison?

Scott had to know that was the case when Scanlan asked her a few years ago to teach a writing class to maximum-security prisoners in upstate New York. The plan was that under her guidance, they would pen essays on any subject they chose — including what got them incarcerated. The three-time Tony nominee agreed before she truly understood what she was getting herself into.

Lest Scott and Scanlan, who co-wrote the piece, be bound by all the facts, they’ve avoided calling their main character “Sherie” or “Scott” but have instead opted for “Volunteer.” But there’s a ring of incontrovertible truth when Volunteer shows up at the prison, is subject to an electronic metal-detector and is slightly amused when her underwire bra sets off the wand. That is, until Volunteer sees that the guard makes staunchly clear that next time he will not allow her to enter if she’s wearing it again.

Agatha Christie’s And Then There Were None involves ten people who learn that one of them is a murderer; here, the six incarcerated men with whom Volunteer will be dealing includes one and only one who is not a murderer. “Can I sit next to him?” Volunteer asks The Warden – and she’s not joking.

When I say “Donald Webber, Jr. plays The Warden,” it seems to be the type of matter-of-fact line that you’d find in any review. But here The Warden is a woman. Be assured that Webber has no trouble assuming the character’s natural femininity as well as her no-nonsense authority.

Most of the time Webber portrays Bey, one of the six inmates. And yet, he and the five others must each play yet another part. This occurs when we move from the prison to a theater’s green room. Volunteer, like Scott, is an actress by trade, so she happens to tell her fellow cast members about her prison experiences. Webber and the others take on all the flamboyance and intelligence expected of theatrical folk, all unctuously full of opinions on how Volunteer should be careful while inside the prison. But once they hear her stories, they segue into “I hope you’re writing this down.”

Should she? Early on, Volunteer assures the inmates “What happens in this room in prison stays in this room in prison.” And yet, an audience is moved from hearing one convict’s penetrating plea “I am not the worst thing I have ever done.” So too is another long-term inmate’s observation that “Circumstances made me a man when all I wanted to be was a boy.” Along the way, we see that the prisoners are brighter than we might have assumed and that they often show a depth of vocabulary.

Still, we get the impression that Scott assured the prisoners of confidentiality, so should she and Dick Scanlan break the promise and betray the men?

Ah, but the Playbill does divulges that the script offers “Additional material by Andre Kelley, Marvin Lewis, Felix Machado, Richard Norat and Jeffrey Rivera,” so all seems to be well.

Or maybe not. Note there are five men credited but six on stage. Did one inmate not want his story told? Did Scott and Scanlan arbitrarily make their sixth-character a composite? Whatever the case, we’re left to provide our own answer to the question “Does the end justify the means?”

(I’d say yes.)

There’s a long-held theatrical belief that playwrights shouldn’t direct their own works; “They just don’t have the objectivity” goes the familiar argument. On the other hand, who knows better what a show should mean or need than the playwright himself, who undoubtedly has long had in his head a distinct feeling on how the lines should be read?

The solution seems so simple: why can’t the playwright and a director co-stage a show? That’s what Mayer and Scanlan have done – superbly. Apparently having the former around to say, “No, Dick, you’re too close to this” and having the latter say “Um, Mike, here’s what I actually meant here” is the way to go, for the collaborative staging has turned out tense and exciting. Has an audience ever been so still on every word – that is, until a sudden line, gesture or moment comes out that makes them laugh?

There’s plenty of laughter, too. The show doesn’t try to make us judge the level of innocence or guilt in these guys; they’re all “used” to being in prison, inured to their fates, and don’t complain about this, that or the other thing; instead, they find humor in dark places and we welcome it.

And how convincing they are! At one point while the inmates were telling their stories, I remembered a 1968 play called The Concept. Instead of using actors to tell the stories of drug addicts from the substance abuse recovery program at Daytop Village, director Lawrence Sacharow chose to put the actual ex-addicts on stage. This spurred me to dig into my Playbill to check out bios and see if I was indeed watching genuine paroled prisoners telling their own stories.

No, they’re all actors up there: Derrick Baskin, Nicholas Christopher, Chris Myers, Ryan Quinn, Daniel J. Watts and Donald Webber, Jr.

That they seem so real in what they’re relating says a great deal about their achievement.

Scott is terrific, too. Does her classroom cheeriness genuinely stem from her personality or from nervousness? She tries to be ho-hum business-as-usual matter-of-fact gives them standard theater-game responses that mark her fears. (“We don’t have to open it up as much.”) Volunteer reveals to us, too, that she has problems of her own, and that life circumstances have put her in her own type of penitentiary. Scott relates these difficulties in a way that makes clear Volunteer is not asking for sympathy; the character takes full responsibility for them, which makes us empathize and like her even more.

The title’s a little strange; it stems from the fingerprinting that Volunteer must endure before she’s allowed inside the prison; her thumb reveals “a whorl inside a loop,” which turns out to be a metaphor: “whorl” is also a verb that means “to move in a twisted or convoluted fashion.” That’s what we see Volunteer and the inmates both experience.

The most fascinating turn of phrase comes while Volunteer is in the green room and off-handedly refers to her fellow actors – not the prisoners, mind you – as her “partners-in-crime.” Scott then has Volunteer give a look of realization that she’ll never use the flippant phrase again in this context. The prisoners are people she’s come to care about, and we’re grateful that Dick Scanlan, Sherie Rene Scott and Michael Mayer have caused the same reaction in us as well.