Muskrat City has been struck by a giant blackout and it's so dark, no-one can see a whisker. A gang of criminal robots is robbing the city's jewellery stores and it's up to Geronimo Superstilton and the Heromice to figure out who's behind the attack. Will our heroes be able to solve the mystery?

Originally published in Italian under the title "La carica dei robottini puzzoni". Based on an original idea by Elisabetta Dami. Book 2 in the Heromice series by Geronimo Stilton.