Horrible Harry thinks he's the world's second-best detective—second only to Sherlock Holmes, of course. But the rest of the kids in Room 3B aren't so sure. So he's determined to prove himself by solving the latest mystery at South School—how to win the new cafeteria contest. He knows the cafeteria lady is using a special mathematical code, but can he crack the code before his classmate Mary tattles on him again? Or will the case go cold right before Harry's eyes?

The kids in Room 3B are holding a Sharing and Caring Tag Sale to earn money for charity. Song Lee and Ida are selling friendship bracelets, Doug is selling books, and Sid is selling delicious, fresh-baked chocolate chip cookies. But something else is on Harry's mind: his grandmother is having money trouble, and Harry wants to help. So he comes up with a plan to raise money for her. The problem is that Harry doesn't realize his plan involves stealing from the class's charity collection! How can Doug stop his friend from becoming a horrible thief? Could the answer come from one of Sid's delicious cookies?

The holiday season is here, and the kids in Room 3B are learning about all the different ways people celebrate. In addition to Christmas and Hanukkah, there's Kwanzaa, Three Kings' Day, Korean New Year, and more. All the talk about holidays has everyone feeling festive. Everyone, that is, except Harry. He doesn't seem to care about the holidays, the class pet, or even the new student in class. It's clear that something is bugging Harry—but what could it be?

Miss Mackle's class is learning about their ancestors, and everyone just found out that Ida's great-great grandmother sailed on the Titanic-and lived to tell about it. Miss Mackle decides to take the class on a riverboat ride to help them imagine what it was like to travel on the high seas like their ancestors did. Harry and his friends are so excited-it's going to be the perfect field trip. All aboard! Room 3B is setting sail!Illustrated by Frank Remkiewicz.