This episode is a pioneering exploration of the latest discoveries concerning the Amazon - by far the greatest river on Earth. It is the river of superlatives, flowing more than 4,000 miles from the Andes to the Atlantic. Its 1,100 tributaries drain the greatest river basin on the planet and along its incredible journey it collects and transports one-fifth of the world's fresh water. Due to its enormous size, it still hides secrets.
The secret lives of the world’s most mysterious cats are brought to light by advances in remote and low-light filming technology. In South Africa, we follow the nocturnal pursuits of the tiny black-footed cat that stakes its claim to the title of the world's deadliest, and in remotest Mongolia we reveal the rarely seen Pallas's cat, at home with her kittens - she hunts by looking like a rock. Finally, in South Africa, we uncover the secret of the serval that thrives amongst the futuristic landscape of Africa's biggest industrial complex. These are remarkable cats, with surprising lives in extraordinary places.