"Theremin: An Electronic Odyssey" is one of the most magical documentaries ever made. Anyone familiar with films like "The Day the Earth Stood Still," "The Lost Weekend" and "Spellbound," or with the 1966 Beach Boys' single "Good Vibrations," knows the eerie sound of the musical instrument called the theremin. But the life of its inventor, a Russian emigre professor named Leon Theremin, has remained virtually unknown until now, with filmmaker Steven M. Martin's tender, dramatic, sometimes suspenseful and always astonishing documentary. Martin shows how Theremin influenced the course of popular and political culture. One interviewee, Robert Moog (inventor of the Moog synthesizer), who credits Theremin with launching the modern era of electronic music in 1920, recalls making his own theremins as a boy using plans from a hobbyist magazine. (The instrument is comprised only of several radio tubes and circuits hidden in a wooden box, with a vertical antenna on the right and a horizontal loop on the left to allow pitch and volume to be controlled by the player's hand movements;. the instrument itself is never touched.) Beach Boy Brian Wilson adds an exuberant, off-the-wall but ultimately lucid monologue about how "Good Vibrations" was created, and musician Todd Rundgren does an affectionate imitation of a theremin. But Martin's greatest good luck was having Clara Rockmore, a virtuoso theremin player/ endearing prima donna/young love of the dashing Theremin during his New York days. Rockmore's sensitive performances prove the instrument is more than a curiosity; though capable of just one note at a time in a range of five octaves, in her hands the theremin sings like a human voice. A somewhat neurotic voice, but never less than musical. In spanning two continents and taking audiences through the Roaring '20s, the Lenin and Stalin eras and beyond, Martin constructs his often whimsical work for maximum drama and insight, and also reveals political secrets from Theremin's life and the profound impact of the professor's other inventions. Directed, written and produced by Steven M. Martin. An Orion Classics release. Documentary. Rated PG for brief strong language. Running time: 85 min.