Mexico City is sinking...The sewers are overflowing, the landfills are closing, and mountains of Trash from iconic celebrations like the Day of the Dead have nowhere to go. But the city is fighting back. Fearless sewer divers descend into pools of raw sewage to unclog drains. The most polluting cars on the road are being crushed. And now, the world’s second largest megalopolis is building the biggest and most technologically advanced sewage tunnel on the planet.