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!

Horrible Harry is at it again in a rollicking story of Field Day adventures, mishaps...and revenge! It’s one of the best days at South School: Field Day! That means bean bag tosses, relay races, and tug of war. When Mr. Deltoid announces students will pair up to compete for a mystery prize, Harry and Doug are determined to win. But at what cost? Harry's sneaky tactics leave Sid and Mary grumbling. They even claim he’s cheating. Harry insists he's playing fair and square. Doug doesn’t know what to think! He must prove his best friend is innocent before his classmates seek Field Day revenge. Can they win and play by the rules, or will the highlight of the year be a horrible disaster?

Miss Mackle is getting married! But she didn’t invite any of her students to the wedding. The kids don’t understand it: a wedding is a time for families to be together, and they are Miss Mackle’s Room 3B family—which is especially important because her father is in the military overseas, and he won’t be home for the wedding. So Harry comes up with a plan to sneak his pals into the wedding ceremony and hide in the back. It seems like the kids are going to make a horrible mess of their teacher’s wedding . . . until they find a way to save the day for all involved.

A story about appreciating and preserving the environment in your own backyard. Doug thought he knew everything about his best friend, Harry . . . until he discovers that Harry has a secret hideout in the woods just outside of South School.Unfortunately, Harry can’t keep his hideout a secret much longer, because the land is going to be sold and turned into a big apartment building—unless he and the rest of the kids in Room 3B can save it. Harry has the idea to turn the lot into a nature center, and his friends want to help after he shows them the beautiful wildflowers, yellow spotted salamanders, and slimy tadpoles. But can Harry persuade the school board to agree, too? Or will his horrible fear come true: losing his hideout forever?

Harry loves creepy-crawly things. But there’s one creepy-crawly thing that even he can’t stand: head lice! So it’s a terrible day when Harry’s friend Doug discovers lice in his hair. To make matters worse, Mary makes fun of Doug for being dirty and convinces the rest of the kids in Room 3B that they can’t go near him. She claims that everything he touches is infested with lice—even the mac and cheese at lunchtime! Doug wants to run away to Siberia instead of facing his classmates South School. But Harry and Song Lee stand by him and declare battle on the bugs. Will Harry defeat the hated lice, or will Doug have to live with these horrible bugs forever?

Nearly every kid in Room 3B is trying to get picked for the South School Safety Patrol Squad—especially Harry. Harry wants a star badge just like his grandpa's, so he works extra hard to be the perfect student: hanging up his jacket neatly, organizing the crayons in rainbow order, and—his favorite part—cleaning up sticky noodles off the floor after lunch. But Doug thinks someone is taking the power of Safety Patrol too far, maybe even using it to cheat at the Spring Book Fair Raffle! This is Harry’s chance to stop the horrible bully and prove that he deserves a special star. Can he do it?

When the diamond on Miss Mackle’s engagement ring disappears, the kids in Room 3B are determined to help her find it—especially Harry. The third grade talent show is coming up, and he wants to show off his skills as South School’s greatest detective. Meanwhile, Doug has no idea what to do for his act. He can’t sing like Dexter, or dance like Ida, or solve mysteries like Harry. Now the best friends have to find both Doug’s talent and the teacher’s diamond, or else the talent show will be a horrible disaster for everyone!

Will the best artist win? The art teacher asks the students of Room 3B to draw posters of things they love, and one of them will get to display his or her artwork on South School's brand-new TV show. Harry doesn't care about the contest. Mary, on the other hand, is convinced that her poster is the best, and she can't wait for her television debut. But if Mary's poster doesn't get selected, then she's going to make horrible trouble for Room 3B--especially Harry!

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?

Horrible Harry says goodbye in the 30th anniversary finale of a beloved series! The last day of third grade is approaching fast, but a farewell to Room 3B isn't the only goodbye Doug has to say this year. Song Lee and Mary are busy preparing an end-of-year present for their favorite teacher, Mrs. Flaubert, but their excitement can't distract Doug from Harry's suspicious silence. When Harry finally admits that his family is moving to a whole other town, Doug can't believe his ears. How will he survive fourth grade without his best friend?! But Harry has a more pressing question: who's that moving in to the empty house across the street from him? And what could these new neighbors mean for their friendship?