Dennis & The Din Makers go on a whistle stop tour of Beanotown, with a special gig planned to rock The Annual Beanotown Jurassic Model Competition - and ruin it for Walter! After failing to impress Gran with their din, she lends them a mythical amp of her own - with a word of warning, which the menaces ignore... and end up creating a sound wave so epic, it literally rocks Beanotown and its residents! The menaces will have to think quickly, and enlist some rather unusual tools, to disarm the legendary Megasonic 20k before any permanent damage is done.