Doctor Knowles and Professor McCork get to the bottom of some of life's biggest science questions. Dr Knowles and Professor McCork ask the question 'How does my heart keep beating?' Backstage, Ms Hucklebuck challenges everyone to solve a tricky riddle. Colin decides to start a new fitness regime which helps Knowles realise that she might need more than pure brainpower for this tricky challenge.

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. This will end but it cannot end well.

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.