A secret teacher party is happening in the library, but who is the party for? Harry and Doug plan to find out, but when they discover Harry's pet cat, Googer, skulking around their classroom, they have to catch him before anyone else does! They chase The Goog all over school—even into places students (and cats) aren't allowed. Will the boys capture The Goog without being caught themselves? Or will Harry's cat get him into the most horrible trouble ever?

Another uproarious caper in the Horrible Harry series, and this time Harry's not the one breaking the rules! Everyone in Room 3B knows that if Miss Mackle sees you playing with toys at your desk, she'll confiscate them for her June Box. So when a substitute teacher catches good girl Song Lee with a pink origami pig, into the June Box it goes. The problem is that this origami was to be a birthday present for Song Lee's grandmother. So Song Lee does the unthinkable: she breaks into the June Box to free her pig. Now Harry, Doug, and the rest of the kids have to work together--before they all wind up in horrible trouble!

Harry leads a mission to place cobwebs all over school, shows the class how to make green slime, and stages a "deadly skit" that has everyone on the edge of their seats.

It’s a horrible day for Harry: a classmate is calling him names; his library book is overdue; he’s last in line for a turn to be the Room 3B VIP. Worst of all, it’s cold and icy outside again, which means no outdoor recess. It’s all too much for Harry—he starts to go cuckoo! Fortunately, there is a solution to Harry’s problems . . . but it comes from a very unexpected source.