"Apart from the known and the unknown, what else is there?" wrote Harold Pinter.

This we know: ACT Theatre's first Pinter Festival has opened with a scintillating bill of two one-acts, the foundation for further exploration of Pinter's singular, highly influential canon. If a case needs to be made periodically for Pinter's greatness, ACT has a fine start on making one.

Staged with utmost lucidity by John Langs and acted with depth, unsparing humor and precision by a terrific Seattle cast, the bill of "The Dumb Waiter" and "Celebration" serves as bookends to the British dramatist's career.

"The Dumb Waiter" (1960) signaled Pinter's emergence as a provocateur worth reckoning with. "Celebration," a hilarious, haunting piece penned 40 years later, was his swan song.

An early distillation of the truth serum Pinter injected into the bloodstream of the tradition-bound British theater courses through "The Dumb Waiter."

Two hit men wait in a gloomy, airless room — a kind of subterranean boiler room in Robert Dahlstrom's oppressive set. Gus (Darragh Kennan) is young, anxious, jumpy as he frets over the job at hand. His colleague Ben (Charles Leggett) tut-tuts over the newspaper and bristles with irritation at Gus' many questions and complaints.

There's an obvious similarity in the existential dilemmas of these men and the two tramps in "Waiting for Godot," by Pinter's mentor and model, Samuel Beckett.

But "Waiter" mingles similar dread, semantic bickering and Mutt-and-Jeff comedy with a mood of violent menace. And the pungent dialogue (studded with pregnant pauses, made organic by the ACT cast) is very much Pinter's.

"You and I, the characters which grow on a page, most of the time we're inexpressive, giving little away, unreliable, elusive, obstructive, unwilling," Pinter once noted. "But it's out of these attributes that a language arises. A language ... where under what is said, another thing is being said."

The loaded verbal byplay of Gus and Ben, interrupted by surreal demands mysteriously conveyed by a dumbwaiter, is semiabstract, open to interpretation.

But it's clear an intense power struggle underlies the dread. Gus and Ben may jockey for control. But both are underlings of an unseen authority whose heartless demands — for blood, or Greek cuisine — won't be denied.

The power jousting goes upscale in "Celebration," a scathing comedy of manners set in a tony London restaurant. Here an underling has the last word, and the cosmic upper hand.

With a smooth waitstaff wearing glazed smiles attending, two well-off married couples celebrate an anniversary while a younger couple dines at a nearby table.

Pinter trashes the worst aspects of Britain's legacy of Thatcherian individualism with relish. The husbands are sexist, money-grubbing boors (Frank Corrado plays the worst of the lot). Their wives are miserable hostages (Anne Allgood's Prue, Julie Briskman's Julie) and, in the case of sexy young Suki (Mariel Neto), a grasping tart.

These obnoxious swells are easy targets for Pinter, whose leftist politics are implied if not specified.

But a waiter (Kennan) periodically interrupts to interject names of famed literati his grandfather supposedly knew. The running litany is outlandish, funny, yet a poignant reminder of a cultural legacy endangered by a social crassness spreading as steadily as global warming.

Langs and his excellent actors and designers convey, with clarity and humanity, what's said and unsaid. In both plays, they honor what's known and unknown in Pinter's singular vision.

Misha Berson: mberson@seattletimes.com