Knowing that the bus was going 'back to school', Luca had pictured something like the school he and Giulia attended in Genova. It was housed on several floors of an ornate old building, on a street that also housed shops and apartments. Humans seemed to like living all piled on top of each other in small spaces, so that everything and everyone they might need was within easy reach. For somebody accustomed to the broad, shallow bottom of the Ligurian Sea, it had taken some getting used to.

This place was not like that. The building, identified by a sign as Flatwoods Middle School, was only a single storey tall, with flat roofs and very few windows. There was a broad open field behind it, where a group of monster children were playing something similar to football. In front of the building was a big car park with rows of young trees and a small fountain on the broad path to the front door.

The fountain was a welcome sight, because by now Luca and Alberto were starting to dry off again. They pushed their way through the kids leaving the bus and ran ahead to jump in the water, rolling around and splashing to get good and soaked.

Unfortunately, there'd been a girl sitting on the fountain rim reading a book. She had eight spidery legs but a humanoid torso and hair in pigtails, and she was wearing a black cardigan with a lace collar and a ribbon choker with an Egyptian ankh. She shrieked as they splashed her, and scrambled to her many feet.

"Sorry, Miss!" said Luca.

She stared at them, uncomprehending.

"We're sea monsters," Luca added.

"Not good if we get too dry," Alberto agreed.

The girl examined her wet book and brushed some water off a page, then scuttled away.

"Will you need to keep doing that all afternoon?" asked Jeanne, as she and Marie ushered the kids towards the buildings.

"Yes, Miss Lavigne," said Luca.

"We'll see if we can't make it easier for you," Marie decided. Jeanne nodded.

Alberto climbed out of the fountain and put his hands on his hips as he considered the building in front of them. "It doesn't look much like your school," he observed. Luca had sent him some photographs in the mail.

Luca nodded. "I don't think it's gonna be much like it inside, either."

Alberto stood there a moment longer then clapped Luca on the back. "It'll be a brize," he said, though there was uncertainty in his voice. "Just..."

"... just stay wet?" Luca guessed.

"Right." Alberto nodded and followed the monster children indoors, head and tail held high. Luca hurried after him.

Flatwoods Middle School had looked quiet from outside, but inside it was absolutely swarming. Monster kids of every possible shape and size were taking things out of lockers or putting them in, talking in groups, or engaged in any of a dozen other activities. Three girls, dressed in uniforms tailored for their varying number of limbs and heads, were poring over a piece of paper and giggling helplessly. Two slug-like beasts, one in a baseball cap, were bouncing a small ball back and forth with their heads, until a red, crocodile-like adult came and confiscated it. A polka-dot creature was fiddling with colourful cube toy as the group went by, and one of the returning kids waved to it.

"Darse por vencido, Miguel!"

The being called Miguel waved back, then returned its attention to its cube.

Alberto decided to try this phrase out. He poked the armoured back of a spiky yellow creature that was holding a large orange ball. "Hey, darse por vencido!" he said with a cheerful grin.

"Uh... sure," the spiky kid said uncertainly.

An alarm suddenly rang. Luca nearly jumped out of his skin. He grabbed Alberto's arm, but nobody else seemed to consider this an emergency. The students shut their lockers and quickened their steps – or their flapping, hopping, or slithering – but they didn't flee the building. Instead, they ended their conversations with their friends and dispersed into various rooms. Luca kept a tight grip on Alberto as they followed their lifelines, Miss Lavigne and the crab boy named Harry, through a particular door.

Inside was a classroom that looked fairly normal at first, but then Luca began to notice the weird details. One wall had a map hanging on it, but it wasn't a map of anywhere Luca recognized. In another place was a poster labelled The Night Sky, but there were no familiar constellations. Above the blackboard was a row of portraits of monsters in old-fashioned clothing.

The desk, however, were entirely familiar, and the students settled down at them much as students did anywhere. Marie-Jeanne ushered Alberto and Luca to two empty seats at the back, where there was a sink on the wall.

"There we go," said Marie. "There's water right there, if you need to wet down again."

"Just try not to disrupt the class too much," Jeanne added.

"Yes, Miss Lavigne," said Luca politely.

"We'll be as quiet as mice," Alberto promised.

Both of Marie-Jeanne's heads nodded, and she went to the desk at the front to begin the lesson. "Well," said Marie," since on a regular day this would be our period for history, let's talk about what we learned at the factory today in light of that. Who can tell me something about the history of the energy industry?"

A scattering of hands, tentacles, wings, and at least one foot went up.

"Yes, Heather." Marie pointed to a girl.

The child in question rather looked like a heather plant, with spiky fur in green and pink. "Scream power was rationed in some places until just five years ago, as a result of the Great Door Crash!" she announced.

"That's correct," said Marie pleasantly. "We grew up in a small town with rationed scream, actually."

Jeanne, meanwhile, chose one of the boys. "Arthur! What can you tell us?"

Arthur was a glossy green slug-like creature with skinny arms and a pair of curling, ram-like horns. "Today was the first Code Black in monster history!" he said excitedly.

This was met by an awkward silence.

"I think that's a little premature," said Marie primly.

"It's possible," Jeanne admitted.

"But not likely," said Marie.

"Everybody in the parking lot was talking about it," said Arthur.

"That doesn't mean it's anything more than a rumour," Marie told him, while Jeanne nodded. "If anything actually happened, I'm sure there'll be an official announcement."

"Or maybe there won't be," said a girl who looked like nothing so much as a dish of blue jelly, with eyes and a pink bow on top. "Maybe they'd hide the truth in order to avoid a mass panic. You all know humans are deadly poisonous."

Luca looked at Alberto and found him looking back, not sure what to make of any of this.

"You mean venomous," said a striped, gecko-like boy, who was wearing glasses. "If it bites you and you die, it's venomous. If you bite it and you die, it's poisonous."

"What if I bite it and it dies?" asked Arthur.

"Then you're venomous," said the boy in the glasses, rolling his eyes. "Duh."

"Humans aren't venomous or poisonous," another kid announced. "It's just that their mouths are so filthy that after one bite you die of infection."

The jelly waved a dismissive hand. "Either way, why would they tell us and risk society collapsing when they could just quietly kill anyone who got contaminated and cover it up? There might have been dozens of incursions and we would never know."

Luca was still damp, but he got up and sidled over to the sink to splash himself again. Alberto did likewise. A few kids looked back over their shoulders at them, but nobody seemed terribly interested.

"Okay, kids," said Jeanne, raising her hands. "Why don't we just..."

"We should ask Harry," Arthur volunteered. "His family owns the place."

Alberto and Luca were forgotten entirely as all eyes – averaging more than two per individual – turned towards the grey crab-like boy.

"I don't know any more than you do," Harry told them. "If there was an incident, Dad might say something about it at supper tonight." He glanced at Luca and Alberto as they returned to their seats, but his eyes didn't linger on them. "If he does, I'll tell you about it tomorrow."

"Yes, but will you tell the truth?" asked the jelly. "You have a vested interest."

"I'll tell you whatever I find out, Michelle," Harry huffed. "On my honour."

"What is honour worth when it comes from the establishment?" asked Michelle.

"Enough!" barked Jeanne, and to Luca's astonishment she breathed a bit of fire. Even Marie seemed shocked by this, and the class recognized it as a sign that their teacher was losing her patiences. They quickly sat up straight and looked attentive.

Marie gently took over again. "Why don't we go back to what Heather said about the Great Door Crash?" she suggested. "Who wants to tell me about that?"

There was less enthusiasm now. For a moment nothing happened, and then with a sigh, one grey hand went up.

"Yes, Harry?" Marie asked, while Jeanne held her mouth shut and exhaled smoke through her nostrils.

Harry looked around smugly. "Between 1939 and 1945 over a hundred thousand closet doors lost their access to the human world. But my grandfather Henry Waternoose the First developed a more efficient way to store and distribute every decibel of scream power that remained, and founded Monsters Incorporated to rebuild the door bank so that now there's more scream than ever."

"Thank you, yes," said Marie.

Jeanne sighed, letting out a final cloud of grey smoke that gathered in the air above her. "Yes, very good, Harry, although it would have been nice if somebody else could have answered that. Socorro, do you have a question?" she pointed to a lizardlike creature with spines down its back and big red eyes, which had raised a webbed hand.

"Why did the doors fail?" Socorro asked.

"Nobody knows," Marie told her. "It's still a bit of a..."

It felt like lightning passed down Luca's spine as he realized he knew the answer, and before he had properly thought about what he was going to do, the habit of school took over and his hand shot up. "They had a war!" he said.

Everybody stared at him.

"Who?" asked Jeanne.

"The humans," said Luca. Belatedly, he realized he probably shouldn't have said anything, but he'd already started now. There was no going back. "That's, uh... that's what my uncle says. They had a big war that went on for years, and thousands of buildings were destroyed, so their closets would be destroyed, too." He was starting to put this together. The monsters used closet doors to get to the human world and... make kids scream? Because they used it as power for something? That sounded weird, but Luca didn't actually know where humans go their electricity from, although it had something to do with lightning, so who was he to say?

"Well, that's certainly an interesting theory," said Marie delicately.

Luca sank in his seat a little, as everybody gave him funny looks. That had happened before, when he'd tried to answer a question in school and had ended up saying something humans thought was weird. Everybody was staring, wondering what was wrong with him, and he wished he could disappear.

Despite that embarrassment, by the time the class was over Luca was pretty sure he had this figured out. In order to get back to Portorosso, all he and Alberto had to do was go back tot he factory and find the door that led to Rocco's closet. It would be easy.

The bell rang, and the kids scooped up their books and filed out of the classroom. Luca and Alberto stopped to wet themselves down in the sink one last time, and missed some minor drama in the process. Somebody shrieked, and they turned around to see the blob named Michelle pointing an angry gelatinous finger at the gecko boy.

"Miss Lavigne!" she wailed, "Lewis stepped in me!"

"You stopped right in front of me!" Lewis protested. He shook a wad of goo off his foot. It dropped to the floor and rolled across it to join back up with the rest of Michelle.

"You'd have seen me if you were looking where you were going, instead of reading a book!" Michelle informed him.

The two continued to argue as they headed into the hall, leaving only four people in the classroom – or perhaps five, depending on whether one counted Marie-Jeanne as one or two. There was the teacher, the boys, and Harry Waternoose.

"Follow me," Harry told them.

Luca no longer had misgivings about this. If Harry's father owned the factory, then they had to stick to him like glue. They would just have to be very careful not to let him see them dry.

"Sir," Luca said, as Harry led them up the hall, "we need to go back to your father's factory."

Harry scuttled up to a locker and opened it. "What for?" he asked.

"We, um... let something there," said Luca.

"I can tell Dad to have people look for it." Harry stashed some books and picked up a bag, then shut the door again.

"You can't," said Alberto. "It's hidden. We have to get it ourselves."

Harry looked suspicious, but for the moment he did not ask any questions. Instead, he made his way through the teeming hallways to the entrance. Alberto and Luca were still good and damp, but seeing this crush of people and knowing now what would happen if they transformed made them jumpy. When they passed a drinking fountain, Alberto took advantage of it to splash his face, then put his thumb on the nozzle to spray Luca, too.

Unfortunately, not all the water went where he intended. Luca heard a startled cry and spun around to see that some of it had hit the spider-like girl in the ankh necklace. She glared at them.

"Sorry!" said Luca.

She wiped water off her face, then scowled and scurried away.

In front of the building, students were running around or sitting on the grass and talking, or getting onto one of a line of yellow buses that were now parked waiting on the street. Luca wasn't looking forward to riding in one of those again, so he was relieved when Harry didn't go in that direction. Instead, their new friend led them to the parking lot, where there was a car waiting.

At least, Luca was pretty sure it was a car. It was car-shaped, and yet very different from the little cars he was familiar with from Portorosso and Genova. It was black, low to the ground, and very, very long, longer than Massimo's fishing boat. The windows were dark so they couldn't see inside, but then one slid soundlessly open to reveal the driver, who appeared to be a blue octopus with a handlebar moustache.

"Hi, Armstrong," said Harry. "This is Luca and Alberto. They're coming over."

"Of course, Master Harry," said the octopus.

They climbed in. Luca had ridden in cars before, and had found them cramped and uncomfortable. This one, however, was spacious with big soft seats that were almost more like sofas. They sat down, and Harry opened a little door under the seat and pulled bottles of cold water out of a tiny refrigerator for them.

"Thank you," said Luca politely.

Alberto opened his bottle and poured the contents over his head. "So was that different from your school?" he asked.

"Kind of," Luca said. "My school is smaller, and we learn about different things, but we do sit at desks and do math problems, and there are maps and things like that."

"That's it? All day?"

"Mostly. We stop for lunch, and once a week if the weather's good we go back at night to use the big telescope."

"And that's fun?" Everything Alberto knew about school was from Luca's letters, and Luca loved school. They read stories, learned history, did experiments, and looked at the stars – every day brought something new! But now Alberto was looking at Luca like he was crazy.

"Yeah, it's amazing!" Luca said with great enthusiasm. "Didn't you learn a lot today? We learned about the Great Door Crash." He started counting things off on his fingers. "We learned that scream power works by vibrating the air molecules, so everything here runs on sound! And we learned that before they learned to get power by scaring kids, monsters would make machines run by roaring into them!"

"Why would we ever need to know any of that?" Alberto asked. "Nobody back home does things that way."

"It's fun just to know it," Luca insisted. "Don't you like knowing that plants are green because the green chemical helps them absorb sunlight, or that the evening star is a whole planet and has phases like the moon even though you need a telescope to see them?"

Alberto blinked at him, and Luca got a sinking feeling. If Alberto thought school was boring, did that mean he didn't like Luca's letters?

"You don't go to school?" Harry asked with a frown.

"Nope!" Alberto sat back with his hands behind his head. "That's Luca's thing."

Now it was the monster boy's turn to look puzzled. "What do you do all day?"

"I work for my Dad," Alberto replied. "My new Dad. My old Dad left, but I got a new one."

That just confused Harry further. "How did you just get a new dad?"

"I moved in with him, and after a while he let me call him that."

Harry gave them a sideways look with all five eyes. "Where are you guys from?" he wanted to know.

Saying the human world was clearly out of the question. Would Harry know where Portorosso or Genova or even the Ligurian Sea were? The map in the classroom hadn't shown anywhere familiar. Monsters clearly know how to get to the human world, though, so what if somebody tracked them down?

"Milano," said Alberto.

"Yeah, Milano," Luca agreed. He looked at Alberto, and Alberto shrugged. Apparently it was just the first place he'd thought of.

The very long black car drove them through the city and out into a neighbourhood with lots of trees and fences. A wrought-iron gate swung open by itself, and they headed up the drive to a house even bigger than Flatwoods Middle School. It was three storyes tall, surrounded by geometric gardens and carefully trimmed trees. It resembled a countryside villa, the sort of places Luca and Alberto had only seen pictures of. Harry cheerfully thanked Armstrong the chauffeur and scuttled up to the door. His guests followed, and before they reached the step, the butler was already there to answer it.

There seemed to be all kinds of monsters in this world and Luca was trying to act like that was normal – nobody seemed shocked by their appearances, so it would be rude to be surprised by anybody else. Even so, he couldn't stop a frightened squeak at what he saw next.

He had heard the word 'cadaverous' used to describe somebody who was very thin or pale, but the creature in the black suit that held the door for them literally looked like a dead body. It was huge and hunch-backed, with blue-grey skin, white hair, and blank white eyes. Making things even worse was that it was otherwise the most human-looking creature they'd met since Louise had dragged them through Rocco's closet door. If Luca had seen this come out of a closet, he'd have screamed enough to keep a whole city lit for a week.

"Hi, Schrecklich," said Harry.

The butler nodded slowly, once, without speaking.

"This is Luca and Alberto," Harry added.

Alberto stood up as straight as he could and grinned awkwardly, trying to look brave. Luca kept partially behind him, and waved.

"We're going in the pool," Harry added.

Schrecklich nodded again, and turned his head to watch them go by. The boys walked fast and kept their eyes in front, not wanting to look directly at this terrifying creature. The door opened onto a big tiled hallway with intricate carpets on the floor and two flights of stairs leading up to the second level. The ceiling was as high as the third story, with balconies looking down and a stained glass dome at the top. From the centre of the dome hung a glittering crystal chandelier.

"I'm gonna go get my trunks," Harry told them, as they stood staring at the room. "You can head out back. Schrecklich will show you the way." He headed up the left flight of stairs.

The boys swallowed and turned to the butler, still not wanting to meet his empty, staring eyes. Schrecklich grunted, and gestured for them to follow him.

The rest of the house was as palatial as the foyer. They passed through half a dozen rooms stuffed with stylish furniture, with thick carpets on the floor and artwork on the walls. In one, a creature dressed as a maid was vacuuming. She had eyes on stalks, one of which turned to watch them go by, but when she saw they were with Schrecklich the butler, it rejoined its mate in keeping track of the cleaning.

Alberto tried very hard to look as if he were too cool to be impressed by this, keeping his lids half-shut and his head facing forward, but Luca could see him glancing around out of the corners of his eyes. Luca himself couldn't help but staring in amazement, and very nearly fell behind once or twice. Each time, as soon as he realized the others were getting ahead of him, he would run to catch up, because this house looked like a place somebody could get lost in and never find their way out. Sea monsters had an innate sense of direction that always told them which way was home, but that didn't help much in an actual maze.

At last the butler slid a glass door open, and they stepped out onto a multi-level wooden patio surrounded by flowers and palm trees. In one spot was an elaborate cushioned swing, in another a hammock, and on the lowest level was a firepit surrounded by comfy-looking ottomans. The centrepiece was a kidney-shaped swimming pool with a diving board, surrounded by beach chairs and sun umbrellas.

"Cool!" Alberto declared, and dived right in, clothes and all.

Luca paused before following him. "Thank you, Sir," he said to the terrifying butler.

Schrecklich grunted again, and turned and went back inside.

Entering the pool brought on an immediate sense of relief. As long as Luca and Alberto were actually in the water, they wouldn't have to worry about being seen drying out. For the moment, at least, they were safe.

"Can you believe how rich these people are?" Alberto asked, kicking water at Luca with one flippered foot. "I bet they've got a whole fleet of Vespas!"

"Harry did say his dad owns the factory," Luca said. If the screams were the only source of power, and the factory provided all the screams, that made sense. Luca wondered again about electricity. Where did it come from? Were the humans who provided it rich like this, or did it work totally differently? "I hope he can get us in without getting caught." They hadn't seen much of it but the factory looked pretty big. Were they going to be able to find Rocco's door again?

"He'll do anything we want," Alberto said confidently. "We promised to show him two humans, remember?"

"You promised," said Luca, still not sure about that plan.

"We'll be home in no time," said Alberto, floating on his back. "Until then, we get to hang out in this palazzo!"

Luca had other things on his mind. "I wonder what people back home are thinking. I mean. Signora Marsigliese would have heard us all shouting and she must have come in and we were just gone." He hadn't thought of that yet... now that he did, it made him want to panic. "Mom and Dad are gonna be freaking out. And Massimo..."

Alberto must not have thought of this either. He stood up with his feet on the bottom. "You think so? Yeah..." he looked uncharacteristically thoughtful. "Yeah, he'll be looking for me." Luca had told him how Massimo had gone to search for Alberto when he'd run off after their argument, and Alberto had told him what had happened after the boat caught fire.

The glass door slid open again, and Luca and Alberto looked up to see Harry scuttling out onto the patio. He hadn't worn any trousers earlier, but now he had blue swim trunks made to accommodate his many legs. Around his waist was a colourful, tyre-shaped inflatable thing, like a malformed beach ball. When he hopped into the water, it kept him buoyant, and he paddled over to them.

"So when do I get to see these humans?" Harry asked.

Luca looked at his friend. This had been Alberto's idea.

"Tomorrow," said Albert. "Once you get us back into the factor.

Harry nodded and smiled, showing off teeth even sharper than the sea monsters'. "I figured," he said. "That's what you hid there, isn't it? The humans? Right?"

Something in Luca's chest tightened. This had already been a bad idea and now he felt like it was getting worse. What was Harry going to think if he figured it out? Or worse, what if he didn't believe they could show him a human, and just threw them out? Luca had never been very good at lying. It was too hard to remember what he'd lied about and make sure it all made sense together, and his mother was too good at finding those holes.

"Um, yes," Alberto decided. "Yes, they are, and we'll show you tomorrow."

"I knew it!" Harry said triumphantly. "Why did you bring humans into our world? You must know they're dangerous." The words were reproachful, but the tone was intrigued.

"They're not, though," said Luca, desperate to tell the truth about something. "All those things people were saying in class, that they're venomous or will shock you or make you sick, none of that is true."

"It isn't? How do you know?" Harry asked.

"Because we hang out with humans all the time," said Alberto. "Some of our best friends are human. My Dad is human. My new Dad. My old dad was a sea monster."

"I go to school with humans," Luca agreed.

"And that's... normal?" Harry couldn't believe what he was hearing.

"Um." Now Luca hesitated. "Not exactly."

"It's not really common," Alberto said. "We're from just about the only place where humans and sea monsters get along."

"In Milano," said Harry.

"Yes, Milano," Luca agreed.

"Will you take me there?" Harry asked.

"Well..." Faltering for the first time, Alberto looked at Luca for help.

Luca shook his head. "I don't think so." It was a bad idea for many reasons, but he picked the one he thought Harry was most likely to agree with. "I don't know if we'd be able to get you back. The lady who found us, Louise, she said they would have to review the door we came in by. So they might get rid of it. It's not worth the risk."

Harry, however, was not worried at all. "I know where they keep the doors for review. It'll be easy to find it. We'll just wedge it open. They can't deactivate an open door. There are safety protocols."

Luca tried again. "The humans will be scared of you. You're not like the monsters they know."

"Giulia's cool," Alberto offered. "We'll just tell her Harry's a friend of ours, and she'll be fine."

"Yeah, but it's not Giulia's house," Luca pointed out. "It's Signora Marsigliese's house, and it's Rocco's room."

"We'll figure it out," Alberto said.

Maybe Alberto was just stringing Harry along. They did very much need for this boy to keep being nice to them. Once they got back to the factory, they could find a way to ditch him. Luca would feel bad about that, but taking Harry to Portorosso would be such a disaster, it actually made him feel a little sick.