The gravely absorbing Swiss movie "The Boat Is Full," opening today at the Outer Circle, faces an uphill battle. The subject matter -- the plight of a group of refugees threatened with deportation soon after setting foot on Swiss soil -- is grim. No comic relief, no glamor. Nevertheless, "The Boat Is Full" is stimulating and rewarding.

The sobriety of writer-director Markus Imhoof is often shrewdly disarming. His restraint tends to conceal an intensity of feeling that surfaces with surprising impact in key images and situations. There's a subtle moral intelligence smoldering behind the film's homely appearance.

Imhoof's flair for incisive, haunting depiction is apparent in the opening sequence, which shows a detachment of Swiss soldiers constructing a stone wall across the mouth of a railway tunnel. Although the incident looks objective, it's also a symbolic summary of the theme. Imhoof intends to disabuse spectators of the comforting myth that his country welcomed the victims of Nazi oppression with open arms. On the contrary, he equates official policy with a stone wall, designed to block or impede the flow of desperate refugees.

The title itself expresses a sardonic note of shame and regret. By the summer of 1942, when the film's story takes place, the government had established an immigration policy so stringent, yet arbitrary, that only deserters from the German Army might be reasonably expected to find it inviting.

Imhoof, who now resides in Milan, has stated his outlook candidly in interviews: "The history of Switzerland ceased to exist in 1515, when the Swiss suffered a defeat at Marignano. What does exist is a superiority complex and attitude of natural selection, and I personally find it abominable when someone in national office today can say that it is to our credit that we survived both wars so well. And that we will survive the next crisis equally well."

Imhoof's movie, his third theatrical feature, expresses the same sentiment, without putting it in so many words. The prelude at the railway tunnel is followed by an ironic change of scene -- to a night train on the German side of the border, from which the small refugee band soon makes its escape. There are five fugitives: a young woman named Judith Kruger (Tina Engel) and her brother Olaf (Martin Walz); an elderly man, Lazar (Curt Bois, once a character actor in Hollywood, notably as Robert Ryan's flunky in "Caught"), and his granddaughter; a German soldier, Karl (Gerd David), who seizes the chance to desert while investigating the train's unscheduled stop; and a little boy, a French stray unrelated to any of the others.

One would-be escapee is left behind in the haste and confusion -- an elderly woman (Ilse Bahrs), evidently the wife of the old gentleman. Our last glimpse of her reveals another aspect of Imhoof's talent for devastating rhetorical strokes. Her nose bleeding, the woman stands helplessly in the cab of the engine, lit by the glow of the furnace. A guard asks her a question whose menacing connotations carry a delayed-action wallop: "Do you prefer head first or feet first?" He's talking about getting down from the locomotive, you realize, but in the long run he might as well be referring directly to that glowing furnace.

The fugitives are discovered the next morning hiding on the property of innkeepers, Franz and Anna Fluckiger (Mathias Gnaedinger and Renate Steiger), who promptly notify the police. By the time a representative of authority arrives -- a border policeman named Peter Bigler (Michael Gempart) -- they have begun to regret that promptness. Initially irked and frightened by the appearance of the refugees, the Fluckigers relent after spending a little time with them. Their sympathies aroused, the hosts grow apprehensive and solicitous on behalf of their unwanted guests and try to assist in formulating a cover story good enough to get around the restrictive regulations.

Hastily contrived, the hoax falls apart as soon as Bigler subjects it to serious cross-examination. One of the disturbing uncertainties of the situation is that one can't be certain what approach, if any, would help this uninfluential little group in dealing with officialdom. It's possible that Bigler, vain about both his status and smartness, is more offended by the attempt to deceive him than anything else.

The major weakness in Imhoof's treatment is his preoccupation with Swiss character. The contradictory feelings and reactions seen in the behavior of the innkeepers and the policeman ring true, but there's no corresponding ambiguity and complexity in the people obliged to trust them. The refugees need more substance.

Imhoof also makes a peculiar casting blunder. The actor cast as the deserter, who poses as the heroine's husband as part of the hoax, is difficult to distinguish from the actor cast as the husband, an internee the wife is desperate to contact.

Like a number of miscalculations, this one seems to be transcended when Imhoof finally reunites husband and wife briefly in the corridor of a municipal jail and the scene explodes with unexpected passion. A lot of quibbles also flutter away during the concluding deportation sequence, set on the Swiss side of a long bridge on a bleak, drizzly morning. Imhoof is capable of a pictorial and emotional concentration that can churn you up without seeming to set you up. Everything looks casually observed, and the tone remains deliberately restrained, but the payoff is high-intensity pathos. No one is likely to mistake Markus Imhoof for a fun-loving director, but he shows indications of emerging as a masterful, serious director.