Aliens are coming... to get up your nose! After their adventures at the beach, Jack and the gang are looking forward to a well-earned rest. But the work of an alien-buster is never done! With rogue agent Bob still on the loose, and evil, gross aliens converging on Earth to steal our snot, there's plenty still to be done. And there's trouble closer to home, too – an outbreak of nits at Jack's school! But when Jack spots the new school nurse sticking out her tongue and eating a nit from a pupil's head, he realises the two problems might just be linked...