Monsterville is a village inhabited by monsters that have grown tired of living among humans. But one day, Hanna manages to break into her world by putting Monsterville at risk. After the initial fright, the monsters will have to fight against worse enemies: Gargoyle and Cyclops, two monsters that will want to use Hanna to permanently close any contact with the outside world ... running the risk of Hanna being trapped forever in Monsterville.
Through a series of unfortunate events, three mummies end up in present-day London and embark on a wacky and hilarious journey in search of an old ring belonging to the Royal Family, stolen by ambitious archaeologist Lord Carnaby.