New York City’s underground infrastructure is concealed by an enormous number of manhole covers that are produced on the other side of the planet.

While foot-traffickers in NYC see the metallic structures as a passable part of the urban landscape, laborers in India toil in dangerous conditions to fabricate the manhole covers.

A documentary called Cast in India, explores the process under which New York’s plethora of manhole covers are made in India, and then exported to the United States.

A trailer for the documentary shows a threadbare work environment in India: Laborers pour searing hot liquid metal into molding canisters, and chisel away at the sanitary castings without protective clothing or even footwear.

Cast in India is directed by Natasha Raheja, an anthropology student at New York University, and explores the lives of the men who produce the innumerable manhole covers peppering NYC’s five boroughs.

New York’s manhole covers are produced with a scarce lack of resources: The castings, which are tread on by thousands of shoes a day, are molded and shaped across the world by laborers who wear no shoes.

Howrah, India, which is an industrial city in the country’s east, is one of the largest exporters of New York’s manhole covers.

The film, which rubs up against the grueling, dirty, and extremely dangerous conditions laborers face, documents worker battles to negotiate a new contract with their employer.

Raheja, consequently, is no stranger to union advocacy and fighting the power herself: Earlier this year, she helped win an intense contract negotiation with New York University, in which the Graduate Students Organizing Committee (GSOC) union was able to ward off impending budget cuts that would have significantly hampered existing programs and NYU worker pay.

The GSOC is affiliated with the United Autoworkers Union, which is one of the most preeminent in the United States.