Fresh off their first successful investigation, Kazu and her friends--March, CindeeRae, and Madeline--are hungry for their next case, which comes when a vandal begins targeting local comic book stores with anti-comic graffiti. March is especially desperate to unmask the villain before his beloved shop, The Super Pickle, gets hit. But when March takes over, the gang starts butting heads.

It doesn't help that Kazu is distracted by another mystery at home: her mom is bedridden and her grandmother has come from Japan to help out, but no one will tell Kazu what's going on. Juggling two investigations is not easy.

When Kazu and the gang trace the vandal's secret identity to one of the most popular superhero characters in the nation, they realize the vandal's revenge plot is much more explosive than they thought. But can they put aside their differences in time to catch this criminal--or will both of Kazu's cases fall apart?