Then there's a gentleman named Gordon Connell, who has been doing shows for decades and decades; he turns up before the lights even go down for Act Two as the earnest but rhythmically-challenged pianist who will be charged with providing accompaniment to the fledgling stand-up comics who are the play's leading characters. To watch and listen as Connell deftly mangles "Yesterday," "The Girl from Ipanema," and other favorites of bygone days is to witness the assured understated comic brilliance of a master; he very nearly steals the show right out from under McCallum (not to mention Jim Dale, who I haven't even gotten to yet)—without uttering a single word.

Mr. Dale, I must now tell you, is the quiet center of Comedians. He plays Eddie Waters, a one-time comedy performer who could have been great, only he retired young and decided instead to teach aspiring stand-up comics like the members of the class who are the focus of this play. Near the end of the play, Waters relates the events that made him give up his own career, and Dale makes the most of the moment, turning a speech that could be trite into a starkly honest and human confession. We're used to seeing Dale, who has starred on Broadway in shows like Barnum and Me and My Girl, gamboling around the stage, inducing waves of audience laughter; here, as the benevolent eye of a hurricane of explosive would-be comedians, he is as compelling as ever.

Raul Esparza, Allen Corduner, Jamie Harris, Max Baker, David Lansbury, and James Beecher portray Eddie's students. They're a disparate lot, united only by their burning ambition to hit the big time in stand-up comedy. Corduner plays a hard-boiled, middle-aged Jewish fellow named Sammy Samuels who trades too much on his ethnicity. Harris and Baker play Ged and Phil Murray, brothers who work together as a double act; Harris makes us understand immediately that Ged is the naturally funny one, while Baker communicates clearly the ways that humor-impaired Phil nevertheless maintains the upper hand in their relationship. Lansbury is George McBrain, a congenial, glad-hander who has a joke for every occasion; I love the way he makes George a regular (and very plausible) guy in spite of the obsessive bids for attention. Beecher is a sad, down-on-his-luck Irishman called Mick Connor. And Esparza is Gethin Price, a diamond-in-the-rough whose hero worship of Eddie has explosive results.

After weeks of instruction under Eddie's wing, they're due on this night to make their onstage debuts (hence the pianist I told you about). McCallum's character, Bert Challenor, is the agent who will be on hand to judge them and possibly offer some of them their first big break. He and Eddie have opposite views of what comedy is about, however, and as soon as the students figure this out, several of them scurry to make adjustments to their acts to try to win Challenor's favor.

Griffiths plays the story out in yeoman fashion: the central conflicts—selling out vs. remaining true to your principles; the desire to uplift and enlarge vs. the urge to ridicule and destroy—are clearly delineated and cleanly stated. So Comedians is solid but unsurprising: the magic comes from the interplay among the characters, and this cast keeps us engaged and involved throughout. The weak link is Esparza, who—though enormously watchable—hasn't crystallized his relationship to Dale's character yet (that may change with time). And, problematically, his stand-up "performance" in Act Two isn't the electrifying show-stopper it needs to be.

But the rest of the Comedians are terrific. And I almost forgot: William Duell, who has made something of a career playing maintenance men (he was, memorably, Continental Congress custodian Andrew McNair in 1776), is splendid as the school caretaker. Watch him tackle, for what you know is the millionth time, the erasure of some naughty words on the classroom blackboard: now that's a comedian.