A witch has fallen in love with Lupo and wants to bewitch him. F&F chase her and save Lupo at the last second. At the National Inventors' Fair Lupo does some mischief and Prof. Knox argues with a colleague. F&F help a troll to pull his long beard out of a noose - and then land underground in front of the troll king. Dad is having a midlife crisis and suspects Mom of having an affair. And indeed, the signs are mounting.