Sitting through ''The Little Drummer Girl'' is like studying a blueprint for two hours. It's one of those jigsaw movies where every word, gesture, and feeling has been cut to fit a ''grand scheme'' that's not very grand. Some of the themes are thought-provoking, but director George Roy Hill scarcely notices. His eyes are fixed permanently on the plot, and distracting details - like ideas and emotions - only seem to get in the way.
Based on a John le Carre novel, the picture revolves around an American actress (Diane Keaton) who carries role-playing beyond the stage and into her private life. That is, she enjoys lying to people. This endears her to an Israeli agent (Klaus Kinski) who's chasing a Palestinian foe. To trap his quarry , he recruits our reluctant heroine into a complicated scheme that tests her acting talent - and emotional strength - to the utmost. She must pose as a lover of the Palestinian's captured brother, infiltrate his cause, and use herself as bait for the final capture. Not even Ingrid Bergman in ''Notorious'' had a tougher job.
There's good dramatic potential in the idea of a woman with dim political urges being plunged into a life-and-death political struggle. Also promising is the moral complexity of Loring Mandel's screenplay, which articulates grievances and excesses of Palestinians and Israelis alike.
But director Hill simply tosses these possibilities at us, never pausing to explore them or bring out their resonance. You feel like yelling ''Wait a minute!'' as the plot charges blindly on, rushing from one arbitrary twist to another with hardly a glance at their implications. This approach works in a movie like ''The Day of the Jackal,'' which has a straight-ahead story and a conventional good-guy-bad-guy structure. But in the many-layered world of ''The Little Drummer Girl'' it seems a waste to ignore every value except Saturday-matinee storytelling of the most conventional, tritely filmed sort.
The movie's rating is R, reflecting torture scenes and rough language.