In math class, Mrs. Shen was cracking some of her better jokes, such as: “There are three kinds of people in the world: Those who can count and those who can’t.”

  That’s not to say everything was absolutely perfect. Hunter Barnes was still a bit of a bully. When he saw Bryce’s green Skittle costume in math class, he said, “What are you? A green pea?” But that was still better than “booger boy.”

  In Bryce’s locker, he found pictures of his family taped inside the door.

  There were no giant talking gummy bears anywhere to be seen. There were no weird creatures of any type.

  It felt like home here. In fact, it felt better than home.

  But did it feel . . . right?

  Bryce didn’t know yet, but he thought he might stick around to see.

  He wasn’t sure how much time that might take. Or how much time he had. Or what time really meant when traveling to different universes.

  Time is tricky like that. And you know what? Maybe it’s a good time to talk about time.

  Chapter Twenty-Four

  DRIVING A HOT-DOG CAR THROUGH THE FOURTH DIMENSION

  There’s a really good book about time. You might have heard of it. It’s called Locker 37: The Rewindable Clock. We don’t want to spoil it so, if you haven’t already, go read it right now. Don’t worry, there’s time.

  In Locker 37: The Rewindable Clock, Mrs. Shen says that “time is change.” Which is true. We mark time by how things in the universe change.

  But time is something else, too. Time is also the fourth dimension.

  What does that mean? Well, to understand it completely, we have to look at the first three dimensions. (Don’t worry, none of them include the burrito dimension.)

  Start by picturing a dot, like the period at the end of this sentence.

  Or, better yet, take out a crayon, put its tip on a piece of paper, and draw a dot. Really. Do it.

  Got that dot? Good. Don’t lift that crayon yet. Because, hate to be the bearer of bad news, but your dot is dimensionless. What you need to do next is move the crayon across the page. Now you have a line. A line exists in . . .

  The First Dimension! Have you ever heard someone refer to a character in a book as one-dimensional? That means there’s not much to them. They’re boring. Like a line, they have just one thing going for them. In the case of a character, that one thing might be that they juggle. That’s it. Juggling is their only characteristic. In the case of a line, their only characteristic is length. Sorry line, but that isn’t enough for us. We’re moving on to . . .

  The Second Dimension! To get there, you need to take your crayon and remove the wrapper. Now, place the crayon on top of the line you just drew. Press down and sweep or spin the crayon across the page in any direction.

  Congratulations! You’ve drawn a shape! Maybe it’s a square. Or perhaps you spun the crayon and created a circle. Heck, you might have moved it all around and made a squiggly thing that looks like a long and winding road. It doesn’t matter. These are all two-dimensional shapes. In other words, they all have length AND width.

  Two-dimensional things are flat like one-dimensional things, but that doesn’t mean they’re boring. TVs, phones, tablets, and computers all entertain, educate, and inspire you using only two dimensions. In fact, some two-dimensional things are entertaining, educating, and inspiring you right now. The words in this book! They’re totally two-dimensional!

  (Unless, of course, you’re listening to an audiobook version. In which case, we’d like the narrator to say the following word: floccinaucinihilipilification. Why? Just because.)

  So yes, the second dimension has some versatility, but not as much as . . .

  The Third Dimension! Otherwise known as 3D! Don’t worry, you don’t need to put on any special glasses. All you have to do is imagine that the shape you drew is now sweeping downward and leaving behind a trail of shapes in the air below it. Like stacks of crayons underneath it melted together. Or like a 3D printer, and it’s printing a solid object for you. It has length, width, and now, HEIGHT! So instead of a square, you have a cube. Instead of a circle, you have a cylinder or sphere. Instead of a flat squiggly thing, you have a . . . tall squiggly thing!

  The third dimension is the dimension we all live in and are comfortable with. It’s the dimension of beds and baseballs, sandwiches and skyscrapers, pygmy hippos and hippy pigs. We don’t need to explain your everyday reality to you, so what we will try to do is explain . . .

  The Fourth Dimension! Time. Time is the fourth dimension. Confusing, huh? Because time doesn’t have a shape, like a line or a square or a grilled cheese sandwich, right? It doesn’t fit in this sequence.

  Or does it?

  Now, this may be a little hard to wrap your brain around, but try to imagine that you could see in four dimensions. In other words, time isn’t just something on an alarm clock reminding you to get out of bed. It’s another direction you can see in.

  Now picture a giant hot-dog-shaped car. (Your family has one of those in the driveway, right?) If you could see in four dimensions, you could see the hot-dog car’s length, width, height, AND everything it’s ever done and everywhere it’s ever been! You can glance at it and see when it was being built in the factory, when it was driven to a hot-dog-eating contest, and when it was chased by the police, and the driver jumped out at the last second before it plunged to a fiery doom in the Grand Canyon.

  To put it another way, if the first dimension (a line) is created by the trail a dot leaves, and the second dimension (a shape) is created by the trail a line leaves, and the third dimension (an object) is created by the trail a shape leaves, then the fourth dimension (time) is created by the trail an object leaves. In other words, all the places the hot-dog-shaped car has ever been or will be.

  But what comes after that? Is there . . .

  The Fifth, Sixth, or Seventh Dimension? Many scientists believe there are actually ten dimensions, all wrapped around each other like some weird piece of cosmological pasta. Holy cosmolotoni! These ten dimensions explain the laws of pretty much everything. Big and small. Old and new. Everything that has been or ever could be.

  If you master the ten dimensions, you can travel through space and time and between universes. Locker 37 was a master of all ten dimensions, and that’s why these fish sticks were known as interdimensional fish sticks. (The author also wanted to write a book with the words interdimensional fish sticks in the title, so that’s a factor, too.)

  We won’t get into all the details of interdimensionality at the moment, because we don’t want to embarrass theoretical physicists by making it super easy for everyone to understand. Then they’d be out of a job.

  For now, let’s focus on those first four dimensions. All you need to know is that Bryce was a three-dimensional object, and he was leaving a four-dimensional trail through multiple universes.

  But where did that trail lead? And could he turn around and travel back along it?

  Chapter Twenty-Five

  BRYCE’S TRAIL

  Bryce decided to stay in the Locker 37,000 universe. He wasn’t sure if it felt right yet. But it sure didn’t feel wrong. He spent the rest of the day at school, where he enjoyed his classes and spending time with his friends. Then, he returned to his house for the evening, where he had a wonderful time seeing his family and trick-or-treating in his neighborhood.

  Everything about this universe was like Bryce’s universe, but better. The candy was more delicious. People like Keisha, who were sometimes annoyed and embarrassed by Bryce in his universe, were always friendly and supportive here. He slept more soundly.

  That’s right. He went to sleep in this universe. More than once! He was that comfortable. In fact, he stayed for more than three weeks. All the way until the end of November.

  He no longer wore the Skittle costume, of course. Though, even if he had worn it, people wouldn’t have cared. Everyone was so accepting.

  On the last day of school before the Thanksgiving break, Hopewell Elementary was serving a special lunch in the cafetorium. Turkey, mashed potatoes, and all the traditional Thanksgiving foods. Bryce had loaded up a full tray.

  He also still had his plate of fish sticks—and they were somehow still steaming hot—but he kept them hidden in a lunch box. And he made sure he had his lunch box with him at all times.

  It was sitting on the table next to him while he was eating his mashed potatoes and talking to Carson. He usually held onto the lunch box, but he was too busy using both his hands to describe how much stuffing he was planning to eat this year.

  “About a googolplex times as much as this,” he said with his arms stretched wide.

  “Looks like you already have lunch, so you won’t be needing that,” Hunter said as he walked by the table, picking up Bryce’s lunch box. Bryce was quick to respond, but not quick enough.

  He grabbed the lid of the lunch box, while Hunter grasped the handle. Pulling in opposite directions caused the box to open and the fish sticks to fly out.

  “Staaaand baaack!” Bryce shouted. And as he did, one of the fish sticks somersaulted through the air . . .

  It flipped once.

  It flipped twice.

  And then it hit him on the tongue.

  His wonderful world went blurry.

  Chapter Twenty-Six

  NO!

  “No!” Bryce shouted as the fish sticks fell to the ground and he found himself in another universe.

  “No, no, no!” he shouted. For this was definitely not a wonderful universe.

  It may have looked like a wonderful one at first glance. Because Bryce was now in a grand ballroom with chandeliers and dining tables. And that was nice.

  But instead of people, the ballroom was full of tornadoes. And that was not nice!

  No joke. This was a universe with small, self-contained tornadoes. And they were all dressed in evening gowns. And tuxedos! Imagine, if you can, fancy clothing with spinning vortexes coming out of the collars, sleeves, and pant legs. And if you can’t imagine that, then take our word for it. It’s strange and terrifying.

  “No!” Bryce screamed again, and the tornadoes moved closer to him. Their vortexes spun a little faster. And the fish sticks started to slide across the floor toward the tornadoes, as if being sucked into a vacuum.

  Bryce dove to grab the fish sticks, and could feel himself being pulled by the tornadoes. The tornadoes formed a circle. Soon they surrounded him on all sides, pulling his arms and legs and head in different directions.

  The fish sticks were spinning on the floor, like helicopter blades. They were right in front of Bryce’s face, but he couldn’t move his arms, so he couldn’t grab them. All he could do was fight fire with fire. Or fight suction with suction, that is.

  Bryce pursed his lips and began to suck in air. The closest fish stick slowly stopped spinning and inched closer to him. This seemed to anger the tornadoes and so they spun faster. Bryce didn’t have much room left in his lungs and he knew he couldn’t do this for much longer. So, he decided to go for one last gasp. Or one last suck, that is.

  All at once, he drew in as much breath as his lungs could hold, which was more than enough. An entire fish stick flew into his mouth and down his throat.

  The tornado world went blurry.

  He ended up in a new universe, but now he had one fewer fish stick. This universe was populated entirely by monkeys. Monkeys monkeys monkeys, as far as the eye could see.

  Not chimpanzees, bonobos, orangutans, or gorillas. Those are apes. We’re talking howler monkeys, capuchins, macaques, baboons, etc. They were wild and frantic and they shrieked and jumped and clung onto Bryce and stuffed two whole fish sticks down his throat.

  Blurry.

  And it kept happening.

  Bryce kept trying to find his way back to the wonderful universe of Locker 37,000, but then he would end up traveling to some odd and dangerous universe. And instead of holding onto and conserving his fish sticks, he would end up eating them whole!

  For instance . . .

  He ate one while having a particularly vivid dream about ice cream in a universe where everyone slept for twenty-three hours a day.

  He was tricked into swallowing three in one gulp by a rascally cartoon rabbit in a universe where cartoons and people lived together.

  And he gobbled down two when he ended up in a universe where the only things people ate were blue jeans. What else could he do? Denim was not delicious. And he was starving.

  It eventually left him with one final fish stick. And it left him in a new universe.

  Chapter Twenty-Seven

  EMPTY

  He was back in the Hopewell Elementary cafetorium, one he mostly recognized. But it was now entirely deserted.

  Tables were flipped over. There were no people and not even a scrap of food anywhere. No tornadoes, monkeys, cartoons, or blue jeans either. A window at the back was broken, letting in a breeze that made the nutrition posters on the walls ripple.

  Bryce didn’t trust this cold and desolate universe. Raising his final fish stick to his mouth, he thought it might be best to lick it and test his luck yet again. Oh, what he would’ve given to be back in the universe with Locker 37,000. But he had no idea how to get back there, and he also couldn’t risk ending up in a universe that was worse. He’d seen plenty of bad and strange ones already.

  So he decided he should at least explore this universe for a bit, to be certain it wasn’t a place he wanted to be. But he held tight to that fish stick, ready to lick it at a moment’s notice.

  The halls were as empty as the cafetorium, except for homework papers that lay scattered on the floor like autumn leaves. One stuck to his foot when he stepped on it, a science worksheet with Keisha’s name on it.

  Keisha! Seeing her name made him both happy and scared. Was she here, too? It didn’t seem like anyone was here. At least not anymore. Something had obviously happened to anyone who was.

  Something bad? Probably.

  Well, when something bad happened, Bryce knew where to turn. He began to run, and in less than a minute he found himself standing in front of Locker 37. Not Locker 37,000. Just good old Locker 37.

  As he dialed the combination, he said to himself, “I hope this works.”

  It did work.

  The door opened.

  But instead of an orange glow, something soft and rainbow colored was inside. It was a creature that had skin that rippled like fabric. It had swirling, glowing, rainbow eyes. It was beautiful and it was terrifying.

  Before Bryce could even scream, the rainbow-colored creature jumped out of the locker. Bryce leapt backward and fell to the floor, dropping his fish stick. Then the creature grabbed his fish stick and escaped with it down the hall.

  Chapter Twenty-Eight

  THE RAINBOW SPECTER

  Bryce recognized this creature. He was pretty sure he'd seen it before, and you can read all about the harrowing encounter in the blockbuster book, Locker 37: The Ridiculous and Wonderful Rainbow Hat. But feel free to finish this book first.

  The creature was known as the Rainbow Specter. It was like a ghost who wore a sheet with all the colors of the rainbow on it. It was supposedly quite dangerous. Bryce had heard that if he touched it, he might end up like a marshmallow that had been zapped in a microwave.

  He needed his fish stick back, which meant he had no choice but to face the danger and chase it. So Bryce started running as fast as he could down the hall, past the empty rooms, all the way into . . .

  Riley!

  She was running through the halls as well. But bumping into Bryce stopped her in her tracks.

  “You!” she shouted.

  “Me!” Bryce shouted back.

  “We were in the Screamin’ Beagles together! Remember that?” she said. “You wore a Skittle costume. And I ate your fish stick!”

  Bryce did remember, because that happened less than a month ago. And he recognized this Riley from the Screamin’ Beagles universe because she was still wearing the same Ping-Pong ball costume.

  But he was also confused. “I thought we talked about this already,” he said. “You told me all about your adventures.”

  “No, I didn’t, because I’m having my adventures RIGHT NOW,” Riley said. “Wait. Maybe that means you met future me? In the past? Is that possible?”

  “Well, I guess the past and the future can sorta be the same thing,” Bryce said as he scratched at his head. “Because technically every single day is called today. And every tomorrow becomes a today. And every today becomes a yesterday. Which means every day is a yesterday, a today, and a tomorrow, and that means that . . . wait, I’m confused.”

  “So am I,” Riley said. “But I think it means that I do make it back to my original universe in the end, doesn’t it? And at the exact same moment that I left. How entirely four-dimensional of me.”

  “Four-dimensional?” Bryce asked, because Bryce hadn’t read Chapter Twenty-Four of this book. But you have, so you’ll understand what Riley said next.

  “If I ended up back where I started, then it means that not only can I travel to different universes. I can also travel to different times, across all four dimensions. Holy vegetarian lasagna, that’s cool. Gotta love those fish sticks!”

  Bryce looked down at her hand. It was empty.

  “But where’s your fish stick?” he asked.

  “Stolen,” she said. “That monster played a similar trick on me.”

  “You mean the Rainbow Specter?”