Dr Knowles and Professor McCork ask the question 'How does my heart keep beating?' Backstage, Ms Hucklebuck challenges everyone to solve a tricky riddle and Colin decides to start a new fitness regime.
Dr Knowles and Professor McCork ask the question `How much plastic is there in the oceans?' Meanwhile, McCork starts his own dodgy campaign to save the planet by not changing his underpants, which gains a worrying amount of traction.
Dr Knowles and Professor McCork ask the question 'Which animal can turn invisible?' and backstage, the annual Brain Freeze hide and seek day is kicking off. Anyone can play but poor McCork is still struggling to grasp the basic rules of the game.
Dr Knowles and Professor McCork ask the question 'Could pineapples grow on the moon?' while battling with a lack of oxygen, homesickness and some bad chocolate etiquette. Colin and Ms Hucklebuck remain at Ground Control in the Brain Freeze studio.
Judge Knowles presides over the Brain Freeze court to try to solve the mysterious disappearance of Ms Hucklebuck's tooth, which she had left out for the Tooth Fairy. There has to be an answer to the question 'Why do we have baby teeth?'.
From the seaside, Doctor Knowles and Professor McCork ask the question `Why is the sea salty?' All is going well until McCork introduces his new sidekick Rocky the seagull and it gets harder for floor manager Colin to keep the show on the road.
Dr Knowles and Professor McCork attempt to answer the almost impossible question `How many plants are there in the world?' Backstage, McCork unveils his mysterious Megaphone of Truth, an odd contraption which makes it impossible to lie.
McCork and Hucklebuck attempt to break the record for the world's biggest ice cream cone in the Brain Freeze studio and Dr Knowles answers the question `Can ice cubes sink in water?'
Dr Knowles and Professor McCork ask the question `Are we all related?' Off air, Colin discovers an old treasure chest owned by his great great great great uncle Percy. Will he embrace his swashbuckling family tradition as a salty sea dog?
Dr Knowles is out in Mongolia and Professor McCork joins from Rio de Janeiro to ask the question `Why does the Earth spin on its axis?' Back in Brain Freeze HQ, Colin attempts to ready Ms Hucklebuck to present the show for the very first time.
Professor McCork and Ms Hucklebuck ask `How does a parachute work?' Back in the studio, Colin and Doctor Knowles have the task of getting them down safely but these things are never straightforward when McCork is involved.
Professor McCork and Doctor Knowles ask `How long would it take to walk the Earth? Meanwhile, the normally fearful Colin embarks on a solo Wilderness Survival Challenge, where things could get very creepy.
It's roller disco day and everybody is having lots of fun, except for Doctor Knowles who can't get the hang of it. The science team investigate the question `How many atoms are there in our bodies?'
Knowles and McCork ask `Why do we make saliva while we eat?' Backstage, the crew await a very special guest: Colin's biker mum, Janis.
McCork and Knowles answer the question `Where does poo come from?' They climb aboard the Pooper Snooper on this special mission and are broadcasting live from the digestive system of Colin the floor manager.