There are bus and truck tours and there are military convoys. While technically the former, the current production of Reginald Rose’s Twelve Angry Men at L.A.’s Ahmanson Theatre is rolling across America with the invincibility, not to mention temperament, of the latter. The Roundabout Theatre Company production, now parked on Temple Street, may be a 50-year-old drama, but thanks to the new engine rebuilt on director Scott Ellis’s fluid blocking, it likely will have the payload of a Brinks truck when it heads out of town on May 6th.

Ellis directed a different cast in the play’s 2004 Broadway debut at Roundabout’s American Airlines Theatre, earning the show critical praise, four Tony nominations, and a round trip National Tour ticket that gets punched in Florida after this and again in Southern California next February at Costa Mesa’s Orange County Performing Arts Center.

This deliberation room drama about compassion versus justice did not develop along the usual play-film-television path. Originally a Studio One teleplay in 1954, it was adapted to film in 1957, becoming director Sidney Lumet’s first feature. It was also the only producing credit its star, Henry Fonda, would ever have. It became a stage play almost as an afterthought when Rose adapted it 1964, yet it did not get to Broadway until the Roundabout staging, which became that company's longest-running hit at 228 performances.

Like Agatha Christie’s And Then There Were None or Peter Greenaway’s Drowning by Numbers, there’s a numerical predictability to the plot of Twelve Angry Men that challenges its director and performers. However, unlike those — and most other — crime stories, the sleuths here are laymen locked in a room with only their notes, their memories, and their prejudices to see them through.

The play opens in the empty Jury Room #2 of Allen Moyer's time-capsule set. We hear the judge (Robert Prosky, in an audio holdover from Broadway) read the jury instructions: In this case, a guilty verdict will carry the death penalty. The jury's decision, guilty or not guilty, must be unanimous, but a guilty verdict must be believed by all 12 to be beyond any reasonable doubt. Even one dissenter will produce a hung jury requiring a retrial.

The 12 men are all white, all middle-aged (except the ancient Juror #9, played by Alan Mandell), and all gainfully employed (again with the exception of the retired #9). They begin with a general assumption that they lean equally toward a guilty verdict. Eleven of them do. Only Juror #8 (Richard Thomas) has misgivings about this rush to judgment. Several things trouble him, not the least of which is lock step with which his fellow jurors are ready to move on with their evenings. It falls to #8 to have his concerns answered or convince the other 11 of the need for doubt.

What keeps this from being an exercise in ticking off the conversions is, for one, Ellis’s unseen magician’s hand. He keeps the men moving without ever intruding or making their actions seems gratuitous. This is necessitated by the stage being raised and half the cast upstage of a big table and the other half with their backs to the audience, yet virtually every comment by a juror propels him up out of his seat or opens him out to the house without it seeming forced.