FOUR YEARS AFTER the terrific mockumentary Waiting for Guffman, about an ambitious, oblivious small-town theater troupe's improbable Broadway aspirations, Christopher Guest has co-written, directed, and acted in another ridiculous little film mining ridiculous little people's ridiculous little lives. His latest collaboration with fellow comic mastermind Eugene Levy is the similarly character-driven, similarly hilarious Best in Show, which follows several dog owners on their quest for the blue ribbon at the 2000 Mayflower Kennel Club Dog Show, with brief detours into hostage negotiation, lesbian publishing, and ventriloquy.

As with Guffman, the cast--many returned from the earlier film, including Parker Posey, Fred Willard, Cathleen O'Hara, and Eugene Levy--worked with little or no scripted dialogue and no rehearsals. Following a plot outline co-written by Guest and Levy, the actors were free to improvise dialogue that progressed the story a certain distance each scene. Obviously, with the wrong talent (say, Pauly Shore or Frank Stallone or "the Coreys"), this would surely result in an abominable failure so dismal that it probably would be prosecuted as a crime against humanity--nothing says "crime against humanity" like bad improv. Fortunately, capable actors and effective editing make Best in Show a seamless comedy that makes good use of intended imperfections. The film succeeds with a sense of humor that is refreshing and uncanned, thanks to the awkward pauses and ugly cadences of people engaged in ordinary conversation no screenwriter could duplicate.

Surprisingly, for a movie about a dog show, we're subjected to very little cheap dog humor: no incorrigible terriers peeing on the legs of distinguished-looking old ladies while embarrassed owners look on, or distempered mutts biting the asses of cranky old next-door neighbors. Instead, we get a distressed Weimaraner spread out on a therapist's couch, its owners (Posey and Michael Hitchcock as dystopian power couple Meg and Hamilton Swan) worrying about whether witnessing them having sex has harmed "their Beatrice"; we get Gerry and Cookie Fleck, a sheepish menswear salesman (Levy) and his sexpot wife (O'Hara) from Fern City, Florida, who sing two-part a cappella ditties about their Norwich terrier, "Winky." Jennifer Coolidge as Sherri Ann Cabot, the much younger wife of a very rich old man, manages one of the film's funniest performances without saying much at all, just standing around looking ridiculous in purple eye makeup and hideous outfits.

Like musical theater in Guffman, the dog show premise is an entertaining thread good for a few solid laughs, but mainly it serves as a gateway to the hilarious assortment of dysfunction and utter weirdness of the film's characters... and people who compete in dog shows are a comic goldmine! The dogs are mildly amusing, but as always, it's the simmering passive-aggressive hatred and unexpected strangeness that's funniest. Then there's Fred Willard as Buck Laughlin, the boorish sports commentator, completely out of his element broadcasting a dog show and--employing one of the greatest American comedic devices of all time--set up opposite a stuffy British guy. I shouldn't have to tell you that nearly every laugh in the film's final half-hour belongs to him.

If you have ever had the misfortune of viewing an episode of ABC's Whose Line Is It Anyway? or any of the thousands of hack improv troupes currently perpetrating their wacky songs about prostate examinations on our country's metropolitan areas, then the thought of a largely improvised movie may have you feeling a bit apprehensive, and with good reason. Usually the promise of wacky, audience-interactive fun disintegrates into a nightmarish flurry of manic gestures and stubborn, over-loud stabs at humor within approximately 90 seconds. Bad improv--obnoxious and desperate improv, the most common improv--is absolutely painful to endure. But this is not TV improv; this is comedy, directed by the man who brought us This Is Spinal Tap, for godsakes (and Almost Heroes, though he can surely be forgiven for that). It is an exercise in trust, I know. But without hesitation, you must trust the price of admission to this film, full of actors who know when to bide time and when to throttle it, perfectly capturing the quirks and odd gaps of another strange corner of human behavior along the way.