From the cruel common cold to shocking smallpox we cough up the disgusting details of snot, sneezes and viruses. Lucy arrives at the studio and is really isn't very well - the show starts but pretty soon thing are going wrong again! Professor Mctaggart takes over from Mark to present the show.

Lovely icky red blood - what is it and why do we need it? How does it transport important things around the body? Bob, the robot just has his first aid badge to get so that he can go to the robot jamboree, the trouble is he hates blood. Mark is stopped just in time by blood expert Charles Drew as he is about to give someone a blood transfusion from a dog!

Explosions, atoms and fiendish forces that bubble, bang & bump! What makes things explode? Lucy has made a mistake in the show's script and now everyone thinks the show is about 'elephants' - it's a disaster especially as they have legendary scientist Marie Curie on the show.

What happens to our bodies in space? Can we live on other planets? Who invented the telescope and how can we make one at home? Mark receives a letter from the head of the channel saying that he is going to be sacked if anything else goes wrong on the show! Lucy, Bob and Professor McTaggart try and make sure they for once everything goes smoothly. Everything seems to be going well until legendary astrologer Galileo arrives and is keen to start selling his telescopes...Lucy is outraged and decides to teach him a lesson!

Poo, pizza and disgusting germs! Why do we poo and how does digestion work? Who was Louis Pasteur and how did he help? Mark arrives at the studio with terrible stomach pains and asks The Shrinkings Scientists to find out what's wrong with him - in their toughest mission yet Dr Sensible, Professor Small and Junior get ready to fly up Mark's nose to investigate.

What nasty invaders live in our homes and on our bodies? Fleas, parasites, worms and every tiny, disgusting thing in between. Mark can't stop itching, but no one knows what's causing it. The Shrinking Scientists get on the case and investigate. Microscope expert Robert Hooke joins them in the studio.

What is the brain and how does it work? Mark arrives in the studio with a new part of pants, 'Smarty Pants' - he has bought them off the internet and claims that they will make him smarter. Lucy is exasperated and has to try and convince him it's load of old rubbish. Professor McTaggart claims that chewing gum is good for your brain.

Bang, crash, wallop! What is a sound? How do we hear? How do our ears work? Inventor of the telephone Alexander Graham Bell joins the team in the studio to talks telephones and...er.. metal detectors?!

Flesh eating plants & dancing flowers are all packed into the show this week. Mark and Lucy both bring in their favorite plant but as always Mark think's his is the best...until it starts to die. It's left to Ancient Greek plant expert Theophrastus to explain what is happening.