Secrets of Everything

The last episode sees Greg under pressure as he and an inflatable friend attempt to dig to Australia. Then he is sucked into quicksand to discover if it's as deadly as the movies make out.

If a penny falls off the top of the Empire State Building and hits someone, will it kill them? In this episode Greg comes under attack - he has his fingers hammered to test a weird painkiller. And then he investigates 'spontaneous human combustion'.

Greg discovers what he needs to become the fastest man on the planet; works out why a boomerang comes back and finds out why bullet proof vests are actually bullet proof. And we find out whether water drains out of the sink the other way Down Under.

This time, Greg asks perhaps the ultimate science question - 'why is the sky blue?' before probing the urban legend that your eyeballs fall out if you sneeze with your eyes open.

Greg Foot discovers whether there's any truth to the urban legend that you could survive in a falling elevator if you jump as it hits the ground. He's prepared to sacrifice his friends too - in an eye-watering exposé of what makes chilies hot.

In this episode, Greg suffers to find out what humans taste like, and he heads to Reading Festival to work out whether the human race could actually shift the planet by jumping at exactly the same time.