Amongst the barren heights and rugged rocks of the Scottish highlands, there is situated Shilmore Castle. The Castle is under threat of being purchased and shipped stone by stone to America by Eugene PortCullis III Jr, a mega-millionaire. Alarmed by this, Olli and Lissa rush to help their friend Sir Humphrey, the castle ghost, who was somewhat upset by the prospect of forced emigration to the New World. Sir Humphrey decides that today, human beings are only scared by invisible ghosts. You must collect eight ingredients for a potion to make the ghost of Shilmore Castle invisible and save the day.