As his class prepares to visit the school library for the first time, a young boy imagines the worst, based on stories he's heard about the librarian, Mrs. Beamster.
After relating all of the horrible things the school custodian, Fester Smudge, is known to have done, a student whose locker won't open needs Mr. Smudge's help.
On the first day of a new school year Mrs. Green's imagination runs wild as she thinks of all the horrible things she's heard about her new class, including that they've sent their previous three teachers into early retirement.
The students in Mrs. Green's class get a bit nervous when she announces she is going to bring in a class pet but will not reveal what it is--letting their imaginations run wild.
Mrs. Green announces that a new student is joining the class, and he is coming from far away. Immediately, everyone makes their guesses about where he is from. Hubie has his own suspicion--the new kid is from Mars!
"Mrs. Green is out sick today. A substitute teacher is coming. What if he is nine feet tall, crashes through walls, and hurls students into outer space! Uh-oh!"--P. [4] of cover.
A boy learns that a dentist will be visiting his school. He hears scary rumors about the dentist, but discovers there is no reason to be afraid of dentists.