As its title suggests, the documentary "Finding Vivian Maier" offers a sustained inquiry, an investigation into the puzzling life story of the title figure, a nondescript nanny who was posthumously discovered to have been a prolific 20th century street photographer.

But in a larger sense, this film from John Maloof (a Chicago historian and photographer who first discovered Maier's work in the previous decade) and Charlie Siskel studies the human condition itself, specifically the roots of our deep and mysterious need to create, even in the absence of an audience.

Maloof serves as our on-camera guide to Maier's art, taking us through her vivid scenes of life in Chicago, New York, France and elsewhere. The movie effectively argues that Maier, who died in 2009, was one of our great photographers, illustrating her knack for capturing images that wedded an intimate, expressive portrait of each subject framed against harsh urban backdrops. The picture gives ample screentime to countless stills and home movies.

It's a useful introduction to Maier's professional achievements, but the films really stands out thanks to the exhaustive interviews with the many men and women who crossed paths with her during her stints as a nanny.

These anecdotes are filled with conflicting memories and perplexing digressions. They underline the central conflict at the heart of the film, as Maloof wrestles with the question of what Maier would have thought of his mission to expose her work. The question of whether Vivian Maier can ever be "found" is answered here, in moments imbued with the notion that it's possible to know someone and to not know them all. Maybe that, ultimately, was the point.