Katty Kay in Washington and Christian Fraser in London return to report on the events that are shaping the world.

Dr Helen Czerski examines the hottest natural phenomenon on the planet - lightning. High-speed cameras show the secrets of upward lightning that's triggered by urban landscapes. Show more

Len Goodman and Lucy Worsley show how the first few decades of the 20th century saw the most rapid and revolutionary change in the history of British dance. Show more

Documentary series. Dr Hannah Fry explores a paradox at the heart of modern maths, and what maths reveals about the fundamental building blocks of the universe. Show more

In the final part of his personal account of Britain's empire, Jeremy Paxman tells the story of how a desire for conquest became a mission to improve the rest of mankind. Show more

Documentary in which Stephen Smith traces the revolutionary beginnings of Dr Zhivago, one of the best-known love stories of the 20th century, written by Boris Pasternak. Show more

Jago Cooper reveals how a cultural tradition that began over 10,000 years ago survived against the odds, following European contact, disease, land theft and oppression. Show more

Len Goodman and Lucy Worsley show how the first few decades of the 20th century saw the most rapid and revolutionary change in the history of British dance. Show more

Documentary exploring the life and work of Grinling Gibbons, who carved masterpieces from wood for the likes of Charles II and William of Orange. Show more

Documentary series. Dr Hannah Fry explores a paradox at the heart of modern maths, and what maths reveals about the fundamental building blocks of the universe. Show more