In 1970, producer Daniel Melnick approached D.A. Pennebaker about making a series of television documentaries of original cast recording sessions for Broadway musicals. First up: the cast album of Company, the Tony-award winning hit from Stephen Sondheim (music and lyrics), George Furth (book), and Harold Prince (producer and director). Pennebaker's document of this legendary 18-and-a-half-hour recording session focuses on the psychological and technical challenges of the task at hand. As one actor puts it, trying to nail the definitive version of this signature Sondheim music can -- well, as the Company lyric goes, it can drive a person crazy. As Sondheim quietly articulates what he wants from the cast, record producer Thomas Z. Shepard expertly parses a great take from a definitive one. At one point, Sondheim tells an actor to keep in mind that this is going to be the permanent recording -- as if anyone in this fantastic ensemble, or the impressive orchestra, needed reminding. The film's climax comes just past hour 14, as Elaine Stritch battles her way through "The Ladies Who Lunch." The late hour, exhaustion, and challenging material add up to the technical equivalent of running a marathon in a hailstorm. Pennebaker, Jim Desmond and Richard Leacock's achievement with this stunning documentary is their ability to illustrate the extraordinary focus and discipline of the entire group -- from the sound technicians to the orchestra conductor to the show leads. And then there's that score. Required viewing (and listening) for musical theater lovers, and for any and all interested in the creative process and artistic endurance.