This article contains major plot spoilers! READ AT YOUR OWN RISK!
Diary of a Wimpy Kid: The Meltdown is the 13th book in the Diary of a Wimpy Kid series. The book was released on October 30th, 2018.
- Greg Heffley
- Manny Heffley
- Rodrick Heffley
- Frank Heffley
- Susan Heffley
- Rowley Jefferson
- Lower Surrey Street Kids (Main Antagonists)
- Night Janitor
- Dennis Tracton
- Jacob Hoff
- Ernesto Gutierrez
- Gabriel Johns
- David Marsh
- Joseph O'Rourke
- Mitchell Pickett
- Speed Bump
- Pervis Gentry
- Baby Gibson
- Sheldon Reyes
- Mrs. Jimenez
- Anthony Denard
- Jeremy Garza
- Jameson Garza
- Marlee sisters
- Emilia Greenwall
- Latricia Hooks
- Victoria Hooks
- Evelyn Trimble
- Trevor Nix
- The Heffleys' Pig
- Mingo Kids
- Great Aunt Dorothy (mentioned)
- Safety Patrols
- Albert Sandy
- Teddy Silvetti
- Jake McGough
- Mr. Yee (mentioned)
- Mrs. McNeil
- Lily Bodner
- Gary (weatherman)
- Shane Browning
- Cassie Drench
- Eric Reynolds
- Dougie Finch
- Guzmans' dogs
- Mrs. Wiley
- Becky Cosgrove
- Goat Man
- Mrs. Drummond (mentioned)
- Fake Greg Heffley
- Marcus Marconi
When the schools get shut down because of a snowy day, the neighborhood transforms into a wintry battlefield. Some rival groups fight over territory, Some rival groups build massive snow forts, and some rival groups stage epic snowball fights. In the cross-hairs are Greg Heffley and his trusty-true to the end-best friend, Rowley Jefferson.
It's a fight for survival as Greg and Rowley navigate against alliances, betrayals, and warring gangs in a neighborhood meltdown. When the snow clears, will Greg and Rowley emerge as heroes? Or will they even survive to see another day 
The story starts off by Greg saying how everybody is outside enjoying the warm weather, but Greg isn't because it's January and it doesn't feel right because it's the middle of winter. Greg then says about how the whole planet is warming up, and humans are to blame. But Greg says that he shouldn't be to blame, as he only recently got onto planet earth (being born). He then says about he hopes that it doesn't warm up too fast, or he would have to ride a camel to school. He then says he heard that the ice caps are melting and the seas is rising and he was trying to convince his parents to buy a house higher up on their hill so that they can avoid the water for longer, but his parents aren't too concerned. It makes Greg nervous that he's the only person in his family worried about it, and if they didn't do something about it now they would wish they did. The seas rising isn't the only thing that is making Greg nervous, as there could be things in the ice caps, and since they are melting they could be free. Greg then says that he saw a movie about a caveman that got frozen in ice, and thousands of years later when it melted he was still ALIVE. Greg didn't know if that could happen in real life, but if it could he says that if it could his night time janitor could be one.
Greg has to participate with his school on International Showcase Week. Back in November, when there was an International Showcase, he wanted the country to be assigned Italy but unfortunately too many people wanted to study Italy. After a random draw by his teacher, it was given to Dennis Tracton. So he was forced to make a project about Malta. However, he forgot all about it and has now to make it for the following day. Since Rowley refused to switch with him, Greg says that he was on his own and hoped his project will be fine.
In order to push kids away, he only pretended to speak Maltese and not English, but after this, a kid in his grade has parents who are from MALTA. Fortunately for him, a huge fight flared up and the bell rings dismissing school.
However, the situation worsens when Susan receives a letter that Greg has to make his project again. Plus, his mother forbids him for screens on weekends as well as Rodrick and Manny. All brothers decide to misbehave in order to prove her that Screen-Free week-ends aren't working.
Greg also says that his mom says that she wants him to make some new friends. But with the exception of Rowley, he has no chance to befriend an another child. Sometimes, he even has to walk in front of Fregley's house which is between his and Rowley's and it's difficult for him.
Greg then explains that the other kids in his street aren't good people for him to befriend, but the worst are the ones who live in Lower Surrey Street because their street part is flat and Greg lives in Upper Street. The two parts can't stand one another and you can't change from a part to the other as Trevor Nix is considered a traitor for moving to Lower Surrey Street.
Greg talks about the pig which was left at a kennel during their Christmas vacation, and when it gets mad about not going with them, Frank sends it to obedience school, but the person who runs the places calls him telling him the pig ESCAPED. Greg's family puts up posters to find it.
Greg wonders if a human being can hibernate, but Greg tells that it's wrong since he know about The Mingos, who live in the woods don't show up in the winter until spring. Greg says so if they're NOT hibernating all winter, who knows what they're doing.
Greg talks about the Safety Patrols as he enjoyed times he stayed in it since it gave him right to have illimitate hot cocoa. But then he gets expelled and nowadays, it only consists on the Safety Patrol.
He also tells how about dirty his neighbors are. When he is sick, he receives some cherry lozenges for his throat which makes him popular for girls.
Because of the cold, Greg and Rowley try to find a place where they could warm up. They finally hides at Gramma's place while she is on vacation but they don't know that Susan actually comes sometimes in order to make her laundry.
To Greg's surprise, Susan isn't mad at him at all, even congratulating him for using his free time for imagination rather than screens. Greg wishes she'd grounded him INSTEAD.
Greg explains that the Safety Patrol is very strict and report anyone who dares to throw a snowball during a school day. They also deserve to walk on the road but don't allow regular students to do it.
Greg says that he has no qualms about snitching and also that due to the snow, all students had to walk barefeet in the school.
The next day, Greg tries vainly to invent a new way to walk on the show, but fails. He also discovers that the janitor cleaned up every classroom but forgot to close the windows and now, it feels like it freezes also inside.
So, the students try to keep warm and use their creativity. The principal then says that the school will close earlier than the previous day, much to the children's delight but since Rowley and Greg have to walk on their way home, instead of taking the bus, they decide to borrow their worst enemies's (The Whirley Street) . At first, they can infiltrate it without being discovered until an incident with a snowball prompts the bus driver to stop the bus and refuse to star it again until the tattletale admits he did it.
Greg and Rowley are forced to run in the woods, and afraid at the idea they could meet the mingos, are saved at the last minute by Frank who drove in order to find them.
The next day, Greg has the house for himself since Manny is at nursery, Rodrick sleeps and his parents are gone. But little does he know is that his mother planned some chores for him. Since he isn't able to finish all of them before his parents return, his mother forces him to play on the snow and also calls Rowley's parents in order to prevent Craig from coming at his house.
Without any option, Greg and Rowley build a fort which is quickly demolished. Frank gives them some advice, and both boys build an another fort but discover that almost every kid had the same idea. Now, they have to fight against the Lower Surrey Street Kids but they make them look exhausted in order to win the battle. They aren't ready to surrender even Trevor Nix betrayed them in order to win against them.
Also, some others clans join in the epic battle such as The Safety Patrol, and The Whirley Street Kids. Even the Mingos came in which causes everyone else to fight them. The Snowplow driver plows all the snow ending the battle.
After the battle, Greg can't remember why they started fighting over, and the weather warms up a lot. Trevor Nix gets accepted in Lower Surrey Street again and Greg just hopes that everyone will be grateful at him if he can make a good strategy which could allow human people to live with robots. Greg says he's glad that there are people like the HERO type out there, but the world needs guys like HIM too. Greg says because if human beings are still around 500 million years from now, it's gonna be thanks to the Greg Heffleys of the world who figured out a way to SURVIVE.
- This is the second purple book, the first being The Ugly Truth.
- This is the 13th book in the series.
- This is the third book to not have the word "Diary" in yellow. The first two books are Dog Days and Hard Luck.
- However, this is the first odd-numbered book to not have the word "Diary" in yellow.
- This is the first book to use two different shades of one color. On the top half of the book, it is colored Blue-ish Dark Purple. While on the bottom half of the book, it is colored Red-ish Dark Purple.
- However, the overall color of the book is still Dark Purple, anyway.
- This is the second book where the words "of a Wimpy Kid" are in purple. The first is Old School.
- This is the first time the subtitle is 3D.
- This is the third time the spine uses these following two colors and they are: Dark Purple and True Blue. The other two books are Double Down which uses these following two colors: Red-Orange and Yellow and The Getaway which uses these following two colors: Azure and Yellow Green.
- Ironically, the those books are in chronological order.
- This is the first book since Dog Days to be released in October.
- This is the fourth book to include a reptile-skin design.
- This is also the third book to include the new Amulet logo.
- This is the sixth book to feature Greg's trademark frown. The others were: Diary Of A Wimpy Kid, Dog Days, The Ugly Truth, Old School, and The Getaway.
- This is the third book to have a resemblance to the story on the cover, after Dog Days. As purple and blue are "cool colours".
- This is the sixth book to take place in winter. The first five books are Diary of a Wimpy Kid, Rodrick Rules, The Third Wheel, Cabin Fever, and The Getaway.
- This is the third time Greg screwed up a project without research.
- Fregley returns in this book. He hasn't appeared since Hard Luck. However he is never seen during the battle.
- On page 164, Rowley and Greg are coming up with a name for their clan. Rowley suggests "Hufflepuff" which is a reference to the Harry Potter Hogwarts house, but Greg says he wants a more original name.
- Flat Stanley is mentioned on page 141. Greg says that he wants a TV on his ceiling, but he wants it installed by someone who knows what they're doing so he isn't "the next Flat Stanley."
- This is one of few books in which Rodrick and Manny have much shorter roles and the second book after The Third Wheel in which except from flashbacks, Rodrick does not bully Greg.
- Greg mentioned on page 215 that the pig is "somewhere warm by now, having the time of his life." This probably means the pig will probably not return in Book 14, but it is unknown.
- At one page, Joseph O'Rourke is refered as "Joe O'Rourke."