Once lost to the annals of time, the documentary “Redes” (1936) combines the talents of American photographer Paul Strand, Austrian director Fred Zinnemann and Mexican composers Carlos Chávez and Silvestre Revueltas. All four were or became giants in their respective fields, and yet “Redes” faded into virtual obscurity until it was restored in 2009 by Martin Scorsese’s World Cinema Project.

Since then, “Redes” has been rediscovered through home video and the support of advocates such as Scorsese as well as the PostClassical Ensemble, founded in 2003 in Washington, D.C., as “an experimental orchestral laboratory … committed to radically rethinking the concert experience.” Conductor Angel Gil-Ordóñez, the group’s music director, will discuss the film’s significance at the CSO Latino Alliance’s 5th Anniversary Celebration on Sept. 5 in Buntrock Hall. “Redes” will be screened, and members of the Civic Orchestra of Chicago will perform Revueltas’ String Quartet No. 2, and the Latin Grammy-nominated Mariachi Herencia de México will perform songs of the era. (For the DVD’s release, the PostClassical Ensemble recorded the score that will be heard in this screening.)

Co-directed by Zinnemann (in his first credited feature film) and Emilio Gómez Muriel, “Redes” began as a Mexican government-sponsored project to document native workers in their environment, in this case, the fishermen of Alvarado, Veracruz. The fishermen’s leader tries to organize a union, so they can be paid a fair wage for their catch. Strand, one of the titans of modern photography, co-wrote the script and served as the film’s cinematographer. Chavez, one of the film’s producers, recruited Revueltas to write the score for “Redes,” which according to the Criterion Collection, “became an important landmark of Mexican cinema as well as a precursor to Italian neo-realism.”

“Redes” represents an impressive early instance of non-actors employed essentially to play themselves in a narrative based on their actual lives. “There’s not much to that narrative, which sees a Christ-like martyr (at one point depicted delivering a fiery oration in what’s unmistakably an allusion to the Sermon on the Mount) struggling to organize his fellow ill-treated fishermen,” a reviewer for the AV Club wrote. “But ‘Redes’ still has one foot in the silent era, as many non-American films did well into the 1930s, and Zinnemann, with Emilio Gómez Muriel, achieves astonishing stretches of pure visual poetry when observing the fishermen at work or the stately procession of a child’s funeral.”

In his memoirs, Zinnemann recalled, “The film — the first (and last) of its kind — was expected to play a small part in the government’s plan to educate millions of illiterate citizens and bring them out of their isolation. […] The picture was to be made for the Federal Department of Fine Arts, headed by composer Carlos Chávez. We had recruited practically all ‘actors’ from among the local fishermen, who needed to do no more than be themselves. In addition to acting, they carried all the equipment, rowed the boats and did a multitude of other jobs.  … I’m told that some years later the Nazis found the negative in Paris and burned it. A few prints still exist.”

Whether the Nazis found the film and destroyed is up for debate. What remains certain, according to Gil-Ordóñez: “The surprising thing is that the film’s message has not lost its validity. Revueltas remains, perhaps today more than ever, pure dynamite thrown against the walls in Mexico.”