It s Saturday, which means Oskar and Theodore get to go to the library with their dad! It means donuts for breakfast! And it means endless quiet hours lost in stories. But on this not so quiet Saturday, Oskar and Teddy get a rude surprise when they're interrupted by a five-headed, hangry monster! Will Oskar ever get to finish his book in peace? Will Teddy ever get to gorge on his donuts? Or might both of them hold the secret weapons to taming the beast?