Martin Moone is about to finish primary school and feels he hasn’t achieved very much. He’s desperate to get his picture on the school’s Winners' Wall and decides that entering the Invention Convention science competition will definitely earn him everlasting respect. But Martin - along with his teammates Trevor, Padraic and the ever terrifying Declan Mannion - is having trouble coming up with a winning idea.
Martin’s imaginary friend, Sean, comes to the rescue, and together they concoct a plan to beat the snooty kids from the posh school in town. If they can get their hands on some Notion Potion, a mythical brain-boosting beverage, then Martin will have all the ideas he needs. And so the gang embarks on a dangerous (imaginary) journey in their quest to become 'Boyle’s first Junior Genius'.