L'Avventura is not a sequel to La Dolce Vita; it is not social criticism; it is the finest film to reach Boston this year.

Set in the Italian upper class, L'Avventura studies an individual, not a class. It unfolds through personalities instead of tiresome figures transplanted from an Every-man play. And even more gratifying, this gracefully wrought story reveals a person whose uniqueness is respected: it is not a discombobulated tirade against a wayward society.

Antioni has created a brilliantly coherent study of a girl trying to orient herself in a circle of friends who range from the comparatively normal to the very unstable. Claudia (Monica Vitti) is an emotional, rich, oversexed, unattached blonde Italian bombshell who maintains a strange integrity even while entering an affair with her closest friend's fiance.

The men and women who surround Claudia are made real partly through painting extreme characteristics that are easily sustained. But the interplay which fills the plot makes some extremes much more plausible. Claudia's friend Anna, who is engaged to Sandro, has an apparently neurotic desire to get away from him, even though he attracts her. After two hours of Sandro's behavior, it is entirely clear that there is nothing unreasonable about her wish.

Sandro, a rich contract estimator who mouths dreams of the creator he might have been, dominates the film--not as a person, but as an impulsive bundle of sex-oriented sex appeal. From the moment he makes a pass at Claudia--a few hours after Anna has inexplicably disappeared--to the time when Claudia has fallen quite hopelessly in love with him, the film waits upon his comings and goings. He is the least human character in the film, and easily the less attractive, yet his obnoxiously simple character is also Antioni's indirect way of saying there is nothing rational in Claudia's growing obsession.

But there is a peculiar logic to the story, which finds expression in Claudia's changing attitude--distress at Anna's disappearance, shock at Sandro's advances, attraction to Sandro, shame at her behavior, and finally an unreasoned love in which her shame is slowly lost.

Sandro is discounted by Antioni's contempt; Anna disappears; Antioni never gives much attention to either the featherbrained Julia or the calm Patrizia. Only claudia is left. And because she alone remains at the end of the film, the audience must wonder if the story is only that the slob has caught another chick. In the despairing Lo Dolce Vita, this would be the message. But the essential distinction is that things are not the same at the end as they were in the beginning. Claudia has changed, as has Anna if she lives, as has Julia. L'Avventura is a study of Claudia living, not a hymn of despair or a diatribe against society.

The story is obscured by brilliant photography that makes the viewer concentrate on scenes rather than continuity, but the camera work has an expressive clarity and nightmare emotional intensity which speaks even more clearly than the script. It is this visual language, more than words, which says that Sandro sees Claudia as just a new adventure. But the same language portrays emotional tone so clearly that the film's message is clearly lodged in Claudia's changing attitude.

If you go to L'Avventura looking for La Dolce Vita you will see no more than film clips showing people with too much money and too few principles, to whom everything is pointless. But you will also miss a story finely chiseled into a gem of photography.