SAVERIO - All Souls' Church, 16th and Harvard Streets NW. $5 donation requested. 332-8762.

Although curtain time for "Saverio," by the GALA Hispanic Theater, is listed as 8 o'clock, it may be that the play starts half an hour earlier or 20 minutes later.

At some point members of the audience at All Souls' Church start checking their watc hes and looking around, and gradually all become aware that the work is in progress.

The process of becoming aware of what "Saverio" is about is similarly gradual. Set in an insane asylum, Gabriel Garcia's adaptation of "Saverio the Cruel," a 1936 play by Argentine Roberto Arlt, only slowly reveals its method and point, and remains ambiguous to the end. But it is not the irritating ambiguity of many so-called avant-garde plays, in which the author substitutes oddities or aimlessness for craft and meaning. "Saverio" is a sure-handed satire on the rise of dictatorships, in Latin America or anywhere.

The inmates - or populace - create their own strongman from a hapless "new boy," a butter salesman played with range and depth by Raul N. Rizik. He is at first an idle diversion and a cruel amusement: They force him to assume the postures of power and snicker as they pretend to obey. But while the inmates, led by Marcel Bouquet's wonderfully mad "John," are teasing Saverio, he grows from a rat in a trap to a bear in a cage, and too late it is noticed that someone neglected to lock the door. The animal is loose, and they dance and die to his tune.

GALA (Grupo de Artistas Latinoamericanos ), a nonprofit community theater, has made a virtue of the limitations of the church, using altar, aisle and even pews to happy effect. The play will be presented in English through July 22; in Spanish July 27 through August 5, but it is so tonal and visual that one suspects that a knowledge of neither language is necessary. The work is almost a ballet, with stunning tableaux.

So deft is Garcia's adaptation that the two clinkers in the English script - the expression "grossed me out" and a reference to lasers - serve mainly to highlight its quality. It is fine and challenging theater, and a refreshing surprise to a traditionalist.