With its actors mounted on stools and their scripts propped on music stands, The Exonerated is simple enough to be presented in a prison — except that it might start a riot. The eyesight of Justice is very much in question in this powerful piece of agitprop stitched together by Jessica Blank and Erik Jensen and staged by Bob Balaban. It’s been presented Off Broadway since October with a rotating cast of name actors and unknowns; now it’s on limited tour. Brian Dennehy and Marlo Thomas supply the star wattage for the Boston engagement of the piece, which, culled from interviews of 40 ex-death-row residents who were wrongly convicted of capital crimes and later proved innocent, tells the Kafka-esque stories of six persons.

Not everyone can exit this play and commute the sentences of 167 condemned inmates, as outgoing Illinois governor George Ryan did after seeing The Exonerated (other potent influences included a three-year review of capital punishment in his state). But the stories deftly pulled word-for-word from interviews and trial transcripts and then orchestrated by Blank and Jensen are shocking enough to make even " Dubya " think twice about pulling that switch. The troubling thing about the death penalty, after all, is that you can’t call back a mistake — unless, as in the case of these " exonerated, " the victims have whiled away from two to 22 years on death row but have not yet been killed. (Jesse Tafero, the partner of the only woman represented in The Exonerated, Sunny Jacobs, was not so lucky; the victim, with Sunny, of a botched verdict, he was also the victim of a botched execution that set his head on fire.)

The Exonerated is less a play than interwoven testimony, rife with such small cruelties as an electric chair placed in full view of recreating prisoners. There are 10 stools on stage, in a crowded row before a black background, the two stools on either end perched on platforms. On the floor are the actors representing the six " exonerated " and two women who serve as three wives; elevated are two men who enact assorted cops, lawyers, and judges in the flashbacks to the proceedings that landed the title characters where they didn’t belong. Although one does not wish to indict the South, only the laid-back Illinois organic farmer played by Dennehy (looking so much like a shoo-in for Ted Kennedy: The Later Years that it’s uncanny) was convicted and jailed north of the Mason-Dixon Line. Blank and Jensen do not, however, stack the deck. Whereas race is a factor in some of the convictions, as it is in the play, Jacobs and the play’s most poignant figure, a railroaded Texan named Kerry Max Cook, who spent 22 years being brutalized on death row before DNA evidence proved him innocent, are white.

Spirituality, along with human resilience, looms large in The Exonerated. A former aspiring preacher named David Keaton (Chad L. Coleman) who was wrongly convicted of murder at 18 can’t decide whether he’s lost his faith or become a weather-controlling Jesus. And the docudrama’s folk-wise center is self-described " child a’ the ’60s " Delbert Tibbs (William Jay Marshall), a lapsed seminarian who was doing a Jack Kerouac thing when he was pinned with rape and murder in Florida.

Tibbs supplies the play with both his own wintry poetry and such blunt observations as " if you’re accused of a sex crime in the South and you’re black, you probably shoulda done it, you know, ’cause your ass is gonna be guilty. " He also points out, toward the end, that patriotism isn’t necessarily a kneejerk flag-waving thing: " I know America gets tired of all these people talking about what they don’t have and what’s wrong with the country. Folks say, ‘Well, what’s right with the country?’ Well, what the fuck? To make things better, we ain’t interested in what’s right with it, we’re interested in what’s wrong with it. You don’t say, ‘What’s right with my car?’  "

In the touring production at the Wilbur, there is little to look at but the acting, which is conversational yet arresting. Dennehy is low-key believable rather than flashy as farmer Gary Gauger, who was convicted on the basis of a hypothetical " vision statement " presented in court as a confession; and Thomas’s Sunny is too silky. But Ed Blunt brings fire and humor to Robert Earl Hayes, an African-American horse trainer wrongly convicted of the murder of a white racetrack groupie; and Tracie Thoms nails his sassy wife. And were the excellent Bruce MacVittie, zippy yet vulnerable as the scarred and sensitive Cook, to be accused of stealing the show, he would have to plead guilty.