In the first episode, Andrew looks at how people live in five of the worlds biggest megacities: London, one of the worlds oldest megacities; Dhaka, the worlds fastest growing megacity; Tokyo, the largest megacity on Earth; Mexico City, one of the most dangerous cities in the world; and Shanghai, arguably the financial capital of the world. Andrew compares the sleek skyscrapers and rapid modernisation of Shanghai to the colourful street culture and geographic sprawl of Mexico City.