The men in black of the title are the Kafka-esquely monikered K (a low-key and sardonic Tommy Lee Jones) and J (Will Smith, who is rapidly establishing himself as one of the best comic actors around). They're agents for a secret organization controlling resident aliens -- the outer-space kind. It seems UFO cultists have been right all along and then some: for decades the Earth has been a refuge for extraterrestrial émigrés. It's the job of K and J to keep track of everyone, apprehend illegals, and preserve the secret from a native populace who presumably would panic if they knew the truth. To blend in with the locals, some aliens take the guise of ordinary people -- pawnbrokers, newsstand vendors, and, of course, cab drivers. Others are not so ordinary; covert celebrity extraterrestrials include Newt Gingrich and Elvis. "It's like Casablanca," K explains to newcomer J, "but without the Nazis."

There are no Nazis, but there are some bad guys Bogie never imagined, in particular the Bug, a carnivorous cockroach terrorist the size of a T. rex awkwardly inhabiting the skin of Edgar (Vincent D'Onofrio, whose sack-of-bricks-having-a-seizure gait would win first prize in Monty Python's Funny Walk competition), a farmer whose close encounter of the unkind ends with an especially nasty special effect. Commandeering a roach exterminator's van, the former Edgar heads for Manhattan, where he plans to assassinate a member of an alien royal family, thus inciting an intergalactic conflagration, or something.

Like The Lost World, Men in Black does not list plot as a major factor; unlike Spielberg's film, it does have tone, timing, and attitude. Edgar leads K and J on a chase of mounting absurdity and zestily imaginative carnage and pyrotechnics, but we never lose touch with the human element in the action and comedy. Despite all the awesome ILM hocus-pocus, Sonnenberg still has the wits to make a scene between Will Smith and a #2 pencil a comic highlight. And though the 48 HRS formula of jaded veteran/cocky neophyte is getting a little old, Jones's glints of anarchic wit and Smith's unabashed insouciance bring it back to confident, laid-back life.

Assisting them is the outstanding supporting cast. Rip Torn as agent Zed, K and J's supervisor, brings a canny, weary sense of absurdity to his role. Best is Linda Fiorentino as Laurel, the city medical examiner whose memory of doing alien autopsies must be obliterated by K's "neuranalyzer," a red light that induces selective amnesia. No cold clinician, Fiorentino's Laurel draws on the actress's kinky dominatrix roles, like that in The Last Seduction; she beguiles J with suggestions about what she might be doing after hours in the morgue with the stiffs.

All would be for naught, though, but for Sonnenberg's shrewd, light directorial touch. He seldom shoves his best stuff in your face; his matter-of-fact sangfroid evokes more excitement and hilarity than a lesser filmmaker's exclamation points. Astounding Chuck Avery-like sight gags lurk unremarked in the film's background and margins (J assisting an alien mother giving birth is a highlight), and more quotable tag lines are tossed away than are belabored in the bloated Batman & Robin.

Not everything fits perfectly. From time to time your sheer enjoyment can be disrupted by the realization that none of it makes much sense. And from the opening credit sequence onward -- a pointless pursuit of a dragonfly as it collides with a windshield -- Sonnenfeld relies too much on the adolescent goo factor. Still, as brilliantly summed up in its postscript scene, Men in Black touches on that spirit of inconsequential and profound play that is the essence of the perfect summer movie. It should suit those alienated from the screen by Hollywood's failure so far to provide that.