Of 100 episodes made over 2 years, these are our favourite 12 programmes
The mysterious case of rising death rates in the world's richest country
Nasa is planning a manned mission to Mars. But the challenges are enormous
Climate change dominated the news five years ago but has dropped down the agenda. Why?
How the city of Medicine Hat in Canada, gave every person living in the streets a home
People are living longer, but not saving enough for their old age.
How drugs get into the US via tunnels, “narco-subs” and complex criminal networks
The rising number of cancer cases worldwide poses a challenge for doctors and governments
The National Rifle Association is one of the most powerful organisations in the US
The UN forecasts that the number of people living in Africa will double in 35 years
Activists claim 40% of unarmed men dying at the hands of the police are black.
The lessons from one of the unexpected stars of the race to tackle child mortality
Why have there been no successful prosecutions of top banking executives?