It’s David Mamet at his funniest — until it isn’t. Dorset Theatre Festival opened a brilliant production of Mamet’s masterpiece, “American Buffalo,” with a stellar cast this week at the Dorset Playhouse, one that found humor in the tragedy of the human condition as well as pathos, ending with something rare in Mamet — hope. Mamet, who won the 1984 Pulitzer Prize for “Glengarry Glen Ross,” is best known for his cynical, street-smart theater laced with edgy dialogue crafted for both emotional effect and shock. “American Buffalo” is rife with what has come to be called “Mamet speak” that, while offending some with its blue language, gives these characters authenticity and heightens the drama. “American Buffalo,” which premiered in Chicago in 1977, takes place in a junk shop in Chicago during a single day. Donny, the owner, has sold a buffalo nickel to a customer for $90, but now thinks it’s worth a lot more. He and Bobby, his young protégé, decide to steal it back. However, Teach, a poker buddy of Donny’s, insists that Bobby is too young and can’t be trusted. And furthermore, they should go for the entire coin collection. More than a narrative, “American Buffalo” is a character study of these three men. Society sees them as “losers,” while they think of themselves as “businessmen.” In Dorset’s production, deftly directed with an unusually light touch by John Gould Rubin, these men all become sympathetic. Despite their exterior unpleasantness, they finally reveal an unexpected humanity. Rubin accentuated the intimacy by placing part of the audience on stage, with virtually no staging, for a theater-in-theround effect. At Thursday’s preview performance, Stephen Adly Guirgis delivered a truly rich performance as Donny, sort of the godfather, who sees himself as a solid businessman, which he applies to his criminal tendencies. Treat Williams was irresistible as the amoral, thin-skinned and not-too-bright Teach, who fancies himself a smooth and savvy operator but can’t quite pull it off. Still, it is Oliver Palmer’s authentic and sympathetic Bobby, also not too bright, desperately striving for acceptance, that becomes pivotal. The interaction between Guirgis’ Donny and Palmer’s Bobby created an emotional depth that gave the performance’s final moments real emotional wallop. Despite some minor firstperformance glitches, ensemble acting at its best by all three made the production largely riveting. Rubin accentuated the play’s power and intimacy by sending the actors around the entire stage area with absolutely minimal staging by Chris Barreca. Add to that Stephen Strawbridge’s dramatic lighting and Kate Fry’s seedy costumes, and the result was real atmosphere. Dorset’s fine production of “American Buffalo” enjoys Mamet’s characters as they see themselves as suave and successful, but are really little boys seeking acceptance. It’s funny, it’s tragic and it’s touching. DORSET THEATRE FESTIVAL Dorset Theatre Festival presents David Mamet’s “American Buffalo” Aug. 24-Sept. 2 at the Dorset Playhouse, 104 Cheney Road in Dorset. Performances are at 7:30 p.m. Wednesday-Saturdays, 2 p.m. Sundays, plus 2 p.m. matinees Wednesday, Aug. 30, and Saturday, Sept. 2. Tickets are $39-$45; call 867-2223, ext. 2, or go online to dorsettheatrefestival.org.