DON ARGOTT was never one of those Philadelphians besotted with the Barnes Foundation, the museum of late-19th- and early-20th-century art tucked away in the suburbs.

A 37-year-old documentary filmmaker, Mr. Argott had previously trained his cameras on disparate subjects like a rock-music school and the experiences of four football players entering the N.F.L. draft. And though Mr. Argott attended the Art Institute of Philadelphia and has lived in the city for 13 years, he didn’t understand the passion that surrounded this highly peculiar Barnes Foundation, the subject of his latest film, “The Art of the Steal.”

“Certain people have deep feelings about the Barnes,” Mr. Argott said the other day over tea at the Morgan Library & Museum in New York, his long curly hair and dark glasses noticeable among the suits populating the cafe. “I didn’t understand. I’d never been there.”

That feeling evaporated the moment he set foot in the galleries that housed the Barnes collection, a trove that included 181 Renoirs, 69 Cézannes, 59 Matisses and 46 Picassos, along with countless other items of visual art, ranging from metalwork to Medieval manuscripts to African sculpture.