How could a man, so rich, famous and visible for so long, become an isolated recluse? Recent medical studies shed new light on the life and death of one of America's most intriguing billionaires.

More than 20 years after army scientist Dr Frank Olson falls to his death from a hotel window in 1953, the US government reveals he was involved in secret experiments studying LSD and interrogation.

Maths whiz and child prodigy, Ted Kaczynski found academic glory at Harvard by the age of 16 but strange and dangerous stress tests he took here may have influenced his later rampage which killed 3.

24 astronauts ventured to the moon on a single engine with the Apollo missions. These are the untold stories of NASA's rarely-remembered breakthroughs, harrowing escapes and heartbreaking disasters.