51 Birch Street is a haunting and touching film, a work so intensely personal that it attains a sort of universal power. Documentary filmmaker Doug Block delves into the 54-year marriage of his parents and, in so doing, explores the convoluted relationships of parent and child and that bittersweet inevitability when you realize your parents are just as deeply flawed as, well, the rest of humanity.

Doug's parents, Mike and Mina Block, appear to be typical of many unions of the "Greatest Generation." The two tied the knot shortly after Mike returned from serving in World War II, and they wasted no time beginning a family. The Blocks had two girls and a boy, and settled into a comfortable middle-class existence in Port Washington, New York.

Using a plethora of home movies and old photos, Doug illustrates the close relationship he enjoyed with his mother, an attractive, demonstrative woman whose eyes brim with intelligence. Doug's interaction with his father, however, is decidedly different. Mike Block hailed from a generation in which men did not easily reveal feelings or voice complaints; he is much more comfortable tinkering around in his basement workshop than opening up to his children.

The family is thrown into turmoil when the 78-year-old Mina suddenly dies of pneumonia. Only three months later, Doug's 83-year-old father reconnects with his secretary from four decades earlier. He announces that the two are getting married, and that he will sell the family house at 51 Birch Street before moving to Florida.

Doug is understandably thrown for a loop. With his camera in tow, the filmmaker resolves to dig into the private lives of his parents. Had his dad been unfaithful? Was Mike and Mina's marriage a happy one? And how much do you really want to know about your parents?

The Blocks' story is told with elegant simplicity. Doug conducts lengthy interviews with his father, sisters, family friends and even psychologists and spiritual leaders. The most telling information of all comes posthumously from Mina. A prolific writer, she kept detailed diaries that spanned more than 30 years, a period in which she was obsessively involved in psychotherapy.

Unlike, say, the family-oriented documentary Capturing the Friedmans, the secrets unearthed by Doug Block are not untoward jaw-droppers. Still, they do pack an unequivocal emotional punch precisely because they are relatable and speak to the inner yearnings and frustrations that we all harbor.

I will stop short of revealing any more, since I suspect 51 Birch Street is most effective when the viewer is on the same journey of discovery as the filmmaker. "When it comes to your parents," Doug says in voiceover, "maybe ignorance is bliss." Perhaps. If anything, however, the filmmaker's quest here leads him to a deeper understanding of, and appreciation for, his parents.

I was deeply, profoundly moved by 51 Birch Street, but I suspect that the circumstances of viewers play a big part in how the movie impacts people.

Shot on video and largely reliant on home movies, the full-frame picture quality is as flat and unremarkable as you'd expect under such circumstances. But that doesn't detract in the slightest from one's appreciation of 51 Birch Street. In fact, its raw look adds to its haunting quality.

The mix in Dolby Digital 2.0 isn't flashy at all, but all you need is clear and clean audio, and it is that.

The centerpiece extra is Who Knew? The Block Family Reacts to 51 Birch Street (21:27), an informative prologue about the family since the film's release.

How's this for eclectic? The disc includes a four-minute music video of Mina Block's elderly brother, Josh Vogel, singing a ditty he wrote called "I Flunk Adultery." It's much more charming than it sounds. Finally, the DVD also has a theatrical trailer.

"Everything is circuitous," Mina Block told her son in one of the many home movies he had shot on video. Indeed, filmmaker Doug Block discovers in his remarkable documentary that few things are quite as challenging and revelatory as learning who your parents really are. In telling this very personal story, he has created an ultimately beautiful work that addresses a question that dogs most of us: Who are our parents -- really?