Kuntz puts his best faces forward in sweet 'Fully Committed'

The quest for a dinner reservation never seemed so harrowing, or humorous. In ''Fully Committed," playwright Becky Mode turns dining into a social, if not contact, sport.

The one-man comedy production running at the Lyric Stage stars John Kuntz in 40 roles. And Kuntz certainly shows up with his game face -- or faces -- on in this lightweight yet entertaining play.

The basements of glamorous Manhattan restaurants hold some surprisingly unglamorous things (other than rats), and in ''Fully Committed," the below-grade office at a tony ''global fusion" eatery holds Sam (Kuntz), an underemployed actor whose day job is to make and confirm reservations at one of the hottest restaurants in town. The headset-wearing Sam juggles multiple phone lines, as well as an intercom and a special hot line to the chef, complete with a flashing red light and onerous buzzing. To say it's a thankless job would be a profound understatement. Sam is not only tortured by the socialites who call in for unavailable tables (the phrase ''fully committed" is this Upper East Side restaurant's way of saying ''booked up"), but also by a squad of co-workers who are ludicrous and laughable.

Sam's co-workers are among the best drawn of the myriad identities that Kuntz assumes. There's the tough-talking but insecure Chef, the haughty and manipulative Jean Claude at the front desk, and the conspicuously absent supervisor, Bob. Kuntz's primary tools for creating these people are his vocal and physical flexibility; there are no costume changes to aid him. Each character has its own rapid-fire sound and posture, and Kuntz juggles conversations with several of these identities at the same time.

That Kuntz is up to the task is never in question. He delivers a remarkable performance: more restrained in many ways than might be expected or even encouraged from one of Boston's most unique and periodically outlandish artists. The restraint comes, in part, from the character he's playing: Sam is a veritable saint through all his phone calls. Kuntz's befuddled stare sometimes communicates more than any line of dialogue does. The restraint also comes as a result of Kuntz's mature performance and Spiro Veloudos's attentive direction: Some of the muckety-mucks calling are beyond ridiculous, but Kuntz resists going over the top with his portrayals.

The trade-off of watching Kuntz play 40 roles is that we don't really get to know Sam as well as we might like. The structure of the play and the required acting acrobatics limit the achievable depth. Amid all the reservation antics, a few personal calls flutter through that do shed some light on who Sam is when the phone isn't ringing. His laid-back Midwestern father calls (repeatedly) to sweetly inquire whether Sam will be able to come home for Christmas, a smug actor friend wants to discuss callbacks for a show at Lincoln Center for which both men are auditioning, and his agent's assistant declares that Sam needs to develop a ''strong sense of personal entitlement" if he is ever to have any success.

Kuntz, meanwhile, has little reason to fret about his own success; while Sam is underemployed, Kuntz seems to work nonstop. The sweet, fast-paced ''Fully Committed" is an outright showcase of his considerable talents, and what it lacks in depth, it makes up for in disposition.

Fully Committed

A play by Becky Mode.

Directed by: Spiro Veloudos. Set, Skip Curtiss. Lights, Robert Cordella.

At: The Lyric Stage Company of Boston, through Dec. 23.

617-437-7172, www.lyricstage.com.