Darby Tillis begins his 50-minute autobiographical monologue by admitting he’s not an actor. Instead he’s onstage because of his powerful experiences: he was the first death row prisoner in Illinois to be exonerated, after he spent nine years in jail, framed for a murder he didn’t commit. The impact of those traumatic years is unmistakable in Tillis’s hulking but cowed physicality and in his wrenching original blues songs. But Tillis and director-adapter Laurence Bryan struggle to turn his experience into a cogent narrative, preferring broad hyperbole (death row is “the cruelest form of racism and genocide”) to humanizing detail. The text is full of holes: we know nothing about Tillis’s life before going to prison (except that he shot one man and assaulted another) and little about his prison experience beyond his conversion to Christianity. Tillis doesn’t need to be an actor, just a better storyteller. Through 5/14: Thu-Sat 8 PM. National Pastime Theater, 4139 N. Broadway, 773-327-7077. $15-$20; industry nights Thu. Special Sunday performances available for groups only.