In The Cleaners, Hans Block and Moritz Riesewieck launch an expose on a peculiar underbelly of social media. With a conspiratorial opening that casts whistleblowers in the total anonymity of darkness, we learn about the Content Moderators. These are men and women working for subcontractors hired by Facebook to click through photos, videos, and other content to decide whether or not a piece of content is appropriate for the site.

These mediators are expected to view 25,000 pieces of content per day and decide whether they should delete, allow, or report the content. They have strict guidelines, but that doesn’t protect them from seeing terrorist beheadings, child pornography, suicide videos, and all manner of terrible things.

This thankless job comes with an even darker side to it: the guidelines that these Content Moderators are using can function as censorship just as easily as they can function as protection. It’s a tough line to tread, and each company walks the tightrope in their own way. But the bottom line is clear: someone decides what is okay for you to see.

Did you think that age-old line between art and pornography was blurry? Well, apparently drawing a caricature of Donald Trump with a small penis can be removed for showing nudity and for disparaging his character. Other questions are even murkier. How about the line between reporting Air Strikes in Syria and glorifying a terrorist bombing? Where’s the line between journalism and manipulation, between True Facts and Fake News?

These are not questions that should be left to a few stuffy boardrooms in a handful of Tech Giants, but as The Cleaners clearly shows, this is exactly what is happening. The recent Senate hearings involving Mark Zuckerberg only make The Cleaners look more prescient and alarming.

This review was originally published as part of our 2018 Hot Docs coverage. The Clearners opens today at the Hot Docs Ted Rogers Cinema.