The Japanese, sensibly, designate certain aging masters as official national treasures. It's time we created that rank for George Plimpton. Not that he restricts himself to a narrow craft: He shepherds along his chosen wing of contemporary lit via the Paris Review, its interviews and anthologies; he documents the outer fringes of pop with biographies of cult figures, histories of fireworks; he toils away passionately as a defender of wildlife. And he has conceived and polished into art a new kind of sitcom: the continuing adventures of a pretender among authentic athletes. He also invented Alex Karras, but nobody's perfect, right?

Episodes of the Plimpton serial come along at irregular intervals: football ("Paper Lion"), baseball ("Out of My League"), golf ("The Bogey Man"), boxing ("Shadow Box") and now ice hockey with "Open Net," in which Plimpton samples life in goal for the Boston Bruins. The adventures are as predictable as any sitcom, but done well enough -- R.I.P. Mary Richards, Barney Miller -- that no one cares. Our hero once more risks and eventually suffers humiliation (with meekest good humor, a good sport in the classic sense) in order to illuminate the interior life of the sport at hand.

The formula, reassuringly, hasn't changed, but time has touched "Open Net's" main character. Plimpton is no longer "Paper Lion's" callow innocent trying to fit in; we've seen too much of his TV persona, all gawk-limbed and waffle-mouthed, weary-eyed and patrician as all get out. As we read, the mind's eye now sees that particular Ichabod creep shakily onto the ice, and we ache a little harder -- mindful of older bones -- at the deep foolishness of his presence there.

He is not above using the image for low comedy. The book's dedication is to Saint Lydwina of Schieden, the patron saint of skaters if not of pratfalls, and the big scene is built around a windmilling, tottering crash to the ice, likened to the collapse of an ancient sofa. Plimpton doesn't skate well: His ankles wobble so badly that he is no taller on ice skates than he is barefooted. Woolgathering in goal, he lets his stick slip from his fingers and watches it slide away from him: "In grabbing for it, I felt my skates go out from under; and I went down on my knees with a thump, and then outstretched on my belly as I reached vainly for the stick. I pulled myself up laboriously and skated out to get it. No harm done, because the players were still at the other end, but I heard a voice from the stands -- a teenager's by the sound of it, one of those clear nasal trumpet voices that can drift across a couple of city blocks and a park, 'All right! Great moves out there, Bozo, great moves!' "

The slapstick, however, is only a bone for the traditional hockey fans -- the same ones who have thrown onto the ice, according to one goalie's list, "eggs, beer, soup cans, marbles, an octopus, rotten fish, light bulbs, ink bottles, a dead turkey, a persimmon, a folding chair, and a dead rabbit." The larger intent of "Open Net" is an almost astonished appreciation of the sport and its practitioners. Hockey, and hockey players, turn out to be more worthy than Plimpton had dared hope.

He had been prepared for louts -- from his own experiences among the fans, from watching a sport that employed designated goons. Instead he found hockey players to be good company, more interesting, more at home in the world than the other pro athletes he's come to know. He explains why, and, by astute sociological comparison, why athletes in other sports so frequently fail to charm. The mature Plimpton can do that: He's seen 'em all now, which gives him a vision into the human level of big-time sports that is simply unattainable elsewhere. He's a treasure.

Given the journalistically rigged nature of the experience, the surprise is how effective Plimpton is as everyman. He plays it straight, a fan himself who has lucked into unusual access. He trusts that what strikes him is what will strike us, and he's correct. He brings back things we want to know but would never have had the wit to ask: how goalie pads are donned (it takes him an hour), what Bobby Orr wore between foot and skate (bare skin), how accurate a good shooter really is. (On a bet, from 60 feet, Peter NcNab deliberately hits the inch-wide vertical post of the goal five shots out of 10.) But he verifies these legends almost dutifully, only as a way of getting on with a good-hearted study of quirky souls living a demonstrably crazy life. Good characters are what make a sitcom work.

It's a lovely little book that made me laugh out loud. It's hardly the advertised sojourn in a Bruins training camp, though. Those days are gone forever; this one's more an evening at Plimpton's club -- that honking voice spinning out good hockey stories over brandy and cigars in front of the fire. Which, as it turns out, is not a bad way to learn a little more about the sport.