A simple flush and it's forgotten. But haven't you secretly wondered where it all goes when we go? Join us as we explore this less-than-polite topic, and examine the network of underground pipes and tunnels that carries human waste and excess storm water away. From ancient Rome's pristine sewage-conveying systems, through the disease-spreading, out-the-window system of Europe in the Middle Ages, and into the progressive sanitation engineering of the 19th and 20th centuries, we go with the flow of sewage history. And we sift through the flotsam and jetsam of our cities' sewer systems and delve into the sewers of Paris, Boston, and Los Angeles to study waste management's evolution. We meet a sewer diver (and his robotic counterpart) who inspects and ensures the efficient operation of the conduits; decipher the myths about "treasures" and creatures found in the murky depths; and find out exactly where it goes, how it gets there, and how we've learned to use it to our benefit.