The team heads to humid Hong Kong, where space is at a premium and real estate is the most expensive in the world.

The team are in Mexico City uncovering the hidden systems and armies of people that help run this sprawling megalopolis of over 22 million people. It's crowded, it's congested and this haphazard city sits in a major earthquake zone. Anita discovers how they're trying to stop this megacity from drowning in its own waste, while Ade explores the daily struggle for clean, affordable drinking water. Mexico City has grown at a staggering pace. How on earth does this epic sprawl survive its many daily battles?

The capital of Russia is a city of 13 million people that like to play by their own rules. Ade discovers how Muscovites escape city life with a trip to a Dacha - there's vodka, a Russian sauna, a thrashing with birch leaves and... more vodka. And, in this city forged by power and politics, Dan gets privileged access to one of Moscow's most closely guarded secrets - the Kremlin. Moscow is imposing and radiates military might. How does this city reconcile a communist past with their capitalist present?