King and Queen Halbert have journeyed to the town of Cleanington to open the brand new Scrubbery Barn at the invitation of Roger the Scrubber. Meanwhile, the Book of Monsters drags Jestro to Snottingham - one of the coldest places in Knighton where everyone coughs, has a runny nose and is generally under-the-weather. The BOM demands that Jestro feed him a "snotheiser" ball which will probably make him sick. The BOM explains that if he is sick, he may just produce a whole new breed of magical monsters ... some that the knights would NEVER expect. The BOM gets sick and starts coughing up phlegm globlins and bloblins. The Knights arrive, alerted to what they think is an attack on the town by Snottingham's mayor, Hack Coughmeier. The sickened, sneezy, snotty monsters infect the knights and, more importantly, the knights' NEXO-Shields. Now their NEXO-Powers are infected.