Scritch, scratch...

One day after floor hockey practice, ten-year-old Zack hears some strange sounds in the school gym. But he's the only one in there. It sounds like scratching...and it's coming from inside the walls. As he investigates, he wonders what could be making the sound. Giant spiders? The ghost of a construction worker buried alive when the school was built? Zack soon discovers that the school custodian has not been doing a good job of keeping the school clean.