A modest and surprisingly gentle documentary about -- of all things -- a high-dollar art theft, Stolen is a welcome excursion off the beaten path. First-time director Rebecca Dreyfus and seasoned cinematographer Albert Maysles (he of the celebrated documentary-making Maysles Brothers) ostensibly concern themselves with the biggest art heist in U.S. history, but end up with a sweetly quirky movie about the enduring nature of art.

The tale spins out from the night of March 18, 1990, when two men disguised as police officers forced their way into Boston's Isabella Stewart Gardner Museum and fled with 13 paintings, including works by Rembrandt, Degas, Manet and a Vermeer masterpiece, "The Concert." Sixteen years later, the heist remains unsolved and the artworks are still missing. Meanwhile, the quietly elegant museum, founded in the early 1900s by renowned art collector Isabella Stewart Gardner, still displays the ornate frames that once held the stolen paintings. "The fact that it (the museum) was robbed ... there's something almost rude about it," notes one observer.

But Stolen is interested in more than the crime. Dreyfus includes a slew of interviews -- historians, art scholars, investigative reporters, art thieves, underworld informants, prosecutors, on and on -- to create an expansive mosaic illustrating human endeavor. In particular, Stolen provides a rich explanation of what makes the loss of Vermeer's "The Concert" such a grievous void in the world of art.

In addition, the filmmakers turn their attention to Isabella Stewart Gardner herself. Blythe Danner and Campbell Scott lend their voices for dramatic readings of 19th century correspondence between Gardner and her European art consultant, Bernard Berenson. During these exchanges, Dreyfus makes clever use of vintage black-and-white footage from the early 20th century.

Best of all, however, Stolen finds a wonderful protagonist in celebrated art detective Harold Smith. Outfitted in a bowler hat and black eye patch, he throws himself wholeheartedly into the Gardner case. The man is a marvel, indefatigable despite a face and prosthetic nose that bear the signs of decades of skin cancer. Tantalizing clues emerge from his investigation, threads that seem to link the heist to Boston mobster Whitey Bulger and the Irish Republican Army. In the end, however, the mystery of the stolen art remains impenetrable.

The filmmakers have a palpable fondness for the vivid characters who drift in and out of Stolen, from Harold Smith to a Gardner museum attendant with a profound connection to the ghost of Isabella Stewart Gardner. Like a Vermeer painting, the most memorable aspects of this documentary are revealed in the small details.

While the print transfer (1.85:1 aspect ratio) is fine, the picture quality itself is fairly typical of low-budget documentaries, particularly in the largely naturalistic lighting and flat images.

The Dolby Digital 2.0 audio is clear, crisp and devoid of drop-off or other problems. The track makes excellent use of a Peter Golub's haunting music score.

The supplemental material is worth a look. It includes an eight-minute, 50-second interview with Rebecca Dreyfus and Albert Maysles, a two-minute, 57-second talk with music composer Peter Golub; and three deleted scenes with an aggregate length of six minutes, 13 seconds.

Winner of Best Documentary at the 2005 Sundance Film Festival, Stolen is often captivating but ultimately hampered by the reality of its subject matter. The 13 artworks swiped from the Gardner museum remain lost to the world; Harold Smith died in early 2005 without making much headway in his probe and before the documentary was completed. Aside from the inevitable letdown of the film's inconclusive conclusion, however, Stolen is an oddly charming film well worth seeing.