In "Garde a Vue," the new French import at the Key, the basic situation -- the decisive confrontation between a calm, tenacious homicide detective played by Lino Ventura and an outraged, puzzling murder suspect played by Michel Serrault -- is deceptively static. Designed and shot with considerable dexterity, the movie never looks pictorially confined, although the key scenes take place at the office of Ventura's character, Inspector Gallien, in the civic center of an unidentified seacoast town.

For macabre atmospheric background, the evolving case against Serrault's character, a prominent local attorney named Martinaud, comes to a head on a rainy New Year's Eve -- an eerily festive evening for a showdown. The process of interrogation is augmented by suggestive little inserts that tend to recall the murder scenes in ambiguous ways. The source of these brief, effective flashbacks is never clearly identifiable. They appear frequently in the course of questioning and could represent mental images belonging to either Gallien or Martinaud. They might also be ascribed to the filmmakers, adding another layer to the mystery.

At any rate, interrogation remains the fundamental dramatic method exploited by director Claude Miller and screenwriter Michel Audiard. The feeling that one must be watching a deftly transposed theater piece is evidently a stylish illusion, since the source material turns out to be not a French play but a British crime novel. The intensifying battle of wills and personalities between Gallien and Martinaud, smart antagonists of contrasted type and temperament, are splendidly portrayed by actors who couldn't possibly be better cast.

Certainly no French star could embody the shrewd, honest detective as effectively as Ventura, a beefy-faced, imperturbable image of masculine authority and professional integrity. By the same token, it's impossible to imagine anyone more suited to express the excitable, suspicious nature of Martinaud than Serrault, best known in recent years for impersonating the wildly effeminate half of the gay couple in "La Cage aux Folles." Serrault now embodies -- with extraordinary sharpness and sensitivity -- the humiliation and resentment of a deeply frustrated heterosexual fuddy-duddy, a man of some consequence publicly who feels miserably unhappy in private.

We discover that the sarcastically defensive Martinaud has emerged as the prime suspect in the successive killings of two juvenile girls who were also sexually assaulted. A strong circumstantial case began to form around Martinaud after he reported discovering the body of the second victim, a girl who lived in his own neighborhood. Citing this fact in his own defense, the suspect is reminded bluntly that it may not count for much unless he can supply better alibis for being near the scene of both murders. As Gallien dryly remarks, "The walls of this room couldn't hold the names of all the killers who 'found' their victims' bodies."

Having summoned Martinaud for one more session, Gallien intends to satisfy his own lingering doubts about the inadequacy of those alibis. It's obvious that he's prepared to book Martinaud, that his mind is almost made up. While Martinaud seems an unlikely murder suspect on the face of it, his unexplained proximity to the victims remains irresistibly suspicious. Along with the inspector, you tend to feel that elusive as the motive may be, the crucial facts can point to no one but the respectable yet wretched Martinaud.

Gallien's line of questioning is meant to catch the suspect off guard, but it doesn't violate a basic code of fairness. Martinaud is certainly intelligent and wary enough to fence with Gallien. However, there are two subordinate figures who do have personal grudges against Martinaud, and their interference strong-arms the investigation toward a resolution. Gallien's snide, sadistic partner, played by Guy Marchand, can scarcely conceal his desire to abuse Martinaud and endangers the case by roughing up the suspect when his boss steps out of the office. Martinaud's unloving wife, played by the late, extraordinary Romy Schneider, whose luminous face could persuasively mask motives ranging from smoldering hatred to intense romantic devotion, arrives to volunteer a decisive piece of incriminating evidence, and it's her appearance that sets off the concluding volley of surprises.

"Garde a Vue" remains worth seeing for the performances of the principal players and the sustained theatrical wit and tension between the costars. Miller, a former assistant of Truffaut's who made a striking debut with the underrated character study set at a summer camp for boys, "The Best Way To Get Ahead," again shows a flair for illuminating the contrasts in feeling, personality and prejudice of men forced into a situation of emotional intimacy. Once again, his cinematographer is the marvelous Bruno Nuytten, whose presence always seems to guarantee a distinctively vivid, tactile form of imagery, whatever the subject matter or location requirements.