Discover Hong Kong, where space is at a premium and real estate is the most expensive in the world. Ade heads into the high rises to find people living in tiny spaces no larger than a cupboard. This former British colony, handed back to the Chinese in 1997, is a city driven by trade and commerce and Dan discovers how it's adapting to life in China's embrace while Anita learns about the city's traditions - from bamboo scaffolding to banishing bad spirits on the daily commute. How does this city of contrasts manage the delicate daily balancing act that keeps it on track?

Dan Snow, Anita Rani and Ade Adepitan are in Mexico City, uncovering the hidden systems and armies of people that help run it. Anita discovers how they are trying to stop this megacity from drowning in its own waste.

Moscow is a city that likes to play by its own rules. It is also a place of contradictions, where the most efficient metro system in the world meets the worst traffic jams on the planet. Anita goes bumper to bumper in this city of epic commutes.

Dan, Anita and Ade are in Delhi, capital of India, with a population of 26 million and rising. Anita discovers how this city feeds itself, visiting Asia's largest fruit and veg market. Ade braves the back streets to get a taste of life as a porter.