Director Rubén Abruña takes us on an impressive journey through 16 cities on four continents. He follows the path of our feces, starting with the sewers in Paris and ending with a huge sewage treatment plant in Chicago. The method used worldwide of using sewage sludge as fertilizer turns out to be highly problematic because it contains heavy metals and toxic PFAS chemicals.

Can human waste contribute to food production and combat soil loss? Abruña meets the Poop Pirates from Uganda, who are trying to turn feces into sustainable fertilizer, visits a dry toilet factory in Sweden that produces fertilizer from urine, and discovers innovative sewage treatment plants in Hamburg and Geneva that produce energy and fertilizer from human excrement.

In the end, the director finds answers to the question of how the reuse of human feces can contribute to global food security, environmental protection, hygiene and the mitigation of climate change.