"Oh, absolutely not."

The next morning, Nico and Will stood outside the Big House, watching the camp's white Delphi Strawberry Service van pull up.

Nico crossed his arms over his chest. He frowned at Chiron, who was playing cards with Mr. D on the front porch.

"I know you don't like me shadow-traveling so far," Nico said, "but riding across the country with him would take way too long!"

Argus, the many-eyed giant who was the camp's head of security, parked in front of them. He hopped out just in time to hear Nico's complaint.

"No offense, Argus," Will hastened to add, "your company is wonderful, but driving from here to California would take like a week."

Argus's shoulders slumped. He blinked his large blue eyes—the ones all over his head, the ones on his forearms, the ones on his shins between his safari shorts and his tennis shoes. Nico wished the giant would say something—just to confirm the rumor that he had an eye on his tongue— but as usual, Argus stayed silent. He glumly held up an index finger.

"It would only take one day," Chiron translated. "The van is quite speedy, and Argus was looking forward to the adventure. Besides, Nico, you're correct. I worry when you shadow-travel such long distances. One of these days, you may enter the shadow world and not be able to get back."

The centaur looked at Will for support.

Will winced. "Usually, I'd be on your side, Chiron. But this time, Nico has a point. The sooner we get to Camp Jupiter, the sooner we can help."

"Also, I've come prepared!" Nico reached into the pockets of his bomber jacket. He pulled out a bag of homemade granola bars—gifts from Juniper—and a turkey-and-cheese sandwich that he'd pilfered from the kitchen. "If I start feeling faint, I'll eat!"

"Plus, we'll have the Cocoa Puffs," added Will. "They'll watch out for Nico."

Right on cue, the ragtag army of cacodemons bounced out from their hiding place under the porch. They swarmed Nico's feet, yipping with excitement.

"Ah, but you haven't shadow-traveled with them yet, have you?" Mr. D gave Nico a sinister smile. "How do you know they won't slow you down? Or cause you to spontaneously combust mid-flight?"

"Dionysus..." Chiron chided.

Mr. D gave him an innocent look, like Who, me? "I'm just saying it could happen."

The wine god took a sip from a golden Capri Sun juice pouch. Nico didn't even know Capri Sun came in gold pouches. Maybe they had a marketing deal with the makers of divine nectar.

"Well, if I combust, I combust," Nico said. "I can think of worse ways to go."

Mr. D laughed. "That's the spirit!"

"It is most definitely not the spirit," Chiron grumbled. "Let's not jinx their trip before it begins."

"Oh, grow up, Chi," said Mr. D. "Live a little! Let the demigods make mistakes!"

"Hmph," said Chiron. He looked at Argus. "Thank you, my friend, but it appears we will not need your chauffeur services today after all. You can continue with your normal strawberry-delivery schedule."

Argus didn't seem to like that idea, judging from the thirty or forty stink-eyes he gave Nico, but the giant nodded, got back in the van, and drove away.

"Well!" Mr. D. tossed the Capri Sun over his shoulder. "I do hope your trip to that wretched Camp Jupiter goes well, boys. Keep me updated. And as for you, little demons..." He leaned forward to study the Cocoa Puffs, who retreated behind Nico with a nervous chorus of Eep! Eep! Eep!

"Live your best life," Mr. D told the cacodemons. "Follow your hearts. Sow chaos and discord. Bye, now!" He snapped his fingers and disappeared in a burst of glitter.

"He's never going to change, is he?" asked Will.

Chiron threw his playing cards on the table. "I doubt it. He always disappears just as I'm about to win."

Nico smirked. "I kind of hope he stays the way he is. It's entertaining." He faced Will. "You ready to go?"

Will grabbed the straps of his canvas backpack. "Ready as ever!"

"Please do be careful," said Chiron. "I am not supposed to pick favorites among my charges, but I would be lying if I didn't admit I have grown very fond of you two."

Nico felt heat rise in his cheeks. "Thanks. I promise we'll do our best."

The activities director waved farewell. "And say hello to all our friends there for me!"

Nico waved back, and then led Will down the path toward the woods. The Cocoa Puffs followed, bumping into one another in a race to be closest to Nico.

At the edge of the forest, where the trunk of an old oak tree blocked the morning sun, they found a nice patch of darkness—perfect for stepping into the shadow world.

"Stay close, Puffs," he said.

Grief grabbed one of his bootlaces. The rest of the Puffs formed a chain behind like they were ready to line-dance to "Old Town Road" all the way to Tartarus.

Will took a deep breath. "I'll never get used to this."

But for Nico di Angelo, son of Hades, returning to the darkness came as easily as thought.

He wrapped his arms around Will. Then he pictured their destination: the western entrance of Caldecott Tunnel, high in the Oakland Hills, where traffic whizzed back and forth day and night on Highway 24. Between the tunnel's two main bores, unnoticed by mortals, stood a set of metal doors, always guarded by Roman sentries....

Nico and Will fell into shadow. The sensation was like flying blind at light speed through a sleet storm—not exactly the most pleasant thing. He worried about Will, who had never shadow-traveled this far before. Nico could feel the Cocoa Puffs dragging at his bootlace, as if they'd become heavier in the shadow world. He really hoped they didn't pull the boot off mid-journey. Otherwise, he'd arrive in California with one shoe and no demons.

The experience was over almost as soon as it began. Nico tumbled to his knees in a stand of sagebrush. His head spun. He was dimly aware of Will crawling to one side, retching up his breakfast. The protein bar Nico had eaten earlier was also threatening to come up. The Cocoa Puffs were the only ones who seemed okay. They hopped around in the weeds, yipping excitedly, like Again! Again!

"Will?" Nico called.

"I'm good." More retching. "You?"

Nico got to his feet slowly, fighting off the wooziness. "Yeah. We made it." In fact, Nico couldn't have gotten them any closer. They'd appeared in the median of Highway 24, in a stretch of weeds and wildflowers right at the base of the tunnel. Just outside the guardrails, cars whizzed by in both directions. To the west, foothills sloped into the flatlands of the East Bay. Beyond that, a blanket of fog covered the bay, pierced only by the towers of bridges, and beyond that in the distance, the San Francisco skyline. The air was cool and damp, scented with the pungent tang of eucalyptus trees.

Will stood, wiping his mouth. His forehead was beaded with sweat. "Wow. That view."

"Yeah," Nico agreed. "But look behind you." Will turned. At the top of the slope, just as Nico remembered, metal double doors were fixed in the side of the hill between the concrete art deco facades of the tunnel's entrances. The doors opened, and two Roman sentries came marching toward them. Each wore full legionnaire armor: golden breastplate, plumed helmet, red cloak, with a shield and spear in either hand and a sheathed gladius at their belt. Just your average heavily armed teenagers, strolling down the middle of a highway.

That was quick, Nico thought. He wondered how the sentries had learned of their arrival. Camp Jupiter must have upgraded their surveillance system since his last visit.

The sentries saluted in unison, thumping their spears against their shields.

"Welcome, Nico di Angelo!" called the guy on the left. He had light brown skin and curly black hair overflowing the edges of his helmet. "I am Yazan. This is Savannah. We're here to escort you and the son of Apollo into Camp Jupiter."

"Wow, so formal," said Will, and then he promptly pitched forward into Savannah's arms. She was half his size, but somehow she managed to steady Will without impaling him with her spear.

"Oof," Will said, finding his legs again. "Sorry. Haven't shadowtraveled in a while."

"Y-yes," Savannah said, blushing furiously. "Of course."

She had a freckled face and coppery-red hair braided down to her waist. When she glanced at Nico's feet, her bright green eyes widened. "What are those?"

Nico followed her gaze.

Oh, right!

The Cocoa Puffs peered up at the girl. One of them—Defiance—rolled forward and inflated itself, growing spikes like a puffer fish. The message seemed to be You got a spear? Big deal. Check me out.

Yazan stepped back hastily. "Are those monsters?"

Nico frowned. He didn't like it when that word was applied to the Puffs. "Not monsters. Cacodemons. They're with me."

Yazan seemed to think about this. His instructions had probably not included escorting an army of demonic dust bunnies into camp.

"Very well," he decided.

Savannah scowled. "Yazan, we can't allow even more—"

"They are our guests," Yazan said, cutting her off. "Please, Nico di Angelo, follow us."

Nico wondered what Savannah had been about to say—even more what?—but he didn't have time to ask.

The sentries led Nico and Will up the path and through the metal doors, which slammed shut behind them. Magical torches guttered to life, filling the tunnel with an eerie purple light. The corridor sloped downward into the hillside.

Will shivered. His breath smoked in the cold air. "This is the entrance to Camp Jupiter?"

"Yep," said Yazan.

"But...is the whole camp underground?" Will sounded worried—which was fair, considering that the last tunnel they'd been through had led to Tartarus.

Yazan chuckled. "No, no. Once we're through the tunnel...Well, you'll see."

"Okay," Will said warily. "Cool."

He fished inside the pouch of his hoodie and produced a Ziploc bag of baked goods. He passed Nico an oatmeal raisin cookie. Then he offered the bag to Yazan and Savannah. "Helps with shadow-travel sickness," he explained. "But I've got plenty."

"Uh...I'm good," said Savannah. She was studiously ignoring Defiance, who was dancing around her sandals, trying to pick a fight. "Snacks aren't allowed while on duty."

"Really?" Will looked shocked. "That's a weird rule."

Nico coughed. "He means to say that your rules are different here. But we respect them."

"Yeah," Will agreed, stuffing half a cookie in his mouth. "Respect."

As they made their way through the tunnel, Nico was surprised how quickly his strength recovered. The cookie helped, and his nausea had passed. Now, however, he was starving. Perhaps this was a benefit of staying in one place for months—Nico had built up enough reserved energy to shadow-travel across the country without face-planting.

"I did warn you, right?" he murmured to Will as they walked. "Camp Jupiter is more formal. Stricter. Might take some getting used to."

"I get that," Will said. "I remember Leo Valdez telling me—"

"Leo Valdez?" Yazan whipped his head in Will's direction. "You know the Great and Mighty Leo?"

Will raised an eyebrow. "Uh...yeah. I can attest that he's a great and mighty goofball."

"And sometimes a jerk," Nico added. "He likes to trick people who don't know any better into calling him the Great and Mighty Leo. Also, he doesn't tell his friends when he comes back from the dead."

"What?!" cried Yazan. "The Great—I mean Leo Valdez died?"

"No, he—" Nico put his hand on his forehead. "Don't worry about it. He's very much alive. Shall we continue?"

Finally, a brightness grew at the far end of the tunnel. They stepped into the sunlight, and Will gasped. "Oh. My. Gods."

Nico would always have an affinity for Camp Half-Blood. (And he certainly believed it was the superior camp, thank you very much.) But the idyllic panorama spread out below them was beautiful.

Much like Camp Half-Blood, the Romans' bowl-shaped valley was hidden from the eyes of mortals. Unlike Camp Half-Blood, an entire miniature society was nestled inside this ring of verdant hills.

The Little Tiber etched a glittering blue crescent around the western half of the valley, emptying into a crystal-clear lake right in the center, dotted with triremes and fishing boats.

Just across the river from where Nico stood, the fortifications of Camp Jupiter itself looked as formidable as ever: high wooden walls with sentry towers at each corner, surrounded by a moat lined with sharpened stakes. Inside the walls, identical barracks lined the Via Principalis—everything neat and orderly. Nico could see soldiers of the Twelfth Legion bustling about on their daily routines—marching in columns, polishing their armor, sparring with swords and spears. If a legionnaire from ancient Rome had materialized inside Camp Jupiter, they would have felt right at home. The Twelfth Legion had constructed their base exactly like every Roman legion had for the entire history of the empire.

To the north stretched the Field of Mars—a vast training ground that was part construction zone, part war-game playground, part postapocalyptic wasteland. Nico had almost died on that field a couple of times. The Romans took their training exercises seriously.

To the south, the vast complex of monuments and shrines on Temple Hill glittered in the sunlight. Smoke rose from the altar of the largest temple to Jupiter Optimus Maximus. Somewhere below that, Nico knew, literally in Jupiter's shadow, crouched a much smaller shrine to Pluto—the Roman alter ego of Nico's father.

Finally, Nico's eyes drifted east, across the lake, to the real jewel box of the valley: New Rome. It was a small city, housing barely more than a few thousand, but it was built to have everything a discerning Roman citizen might want. The Forum would be full of merchants and shoppers this morning, Nico imagined, between the gold dome of the Senate House and the gleaming white Colosseum. Somewhere in the city, amid the winding streets, gardens and villas, cafés, and theaters, Nico's friend Tyson the Cyclops ran a bookstore with his girlfriend, Ella the harpy. Percy Jackson and Annabeth Chase would be attending classes at New Rome University.

The idea warmed Nico's heart, but it also made him feel a little wistful. The Romans did one thing very well: they planned. This valley wasn't just a training camp. It offered a home for life to anyone who graduated from the legion. Demigods could live here forever, follow their dreams, get married, raise a family—whatever they wished, all in relative safety.

It was the ultimate lesson in being present, Nico thought. Staying put. Living life. All those things Mr. D had been trying to teach him. Maybe that's why the place made him feel so uncomfortable.

"Welcome to our camp," said Yazan proudly.

"You're kidding me." Will gave Nico an accusatory look. "This is Camp Jupiter? You did a terrible job describing it!"

Nico shrugged. "I still prefer our slice of woodsy chaos. But yeah, this place is gorgeous."

Savannah marched over to a nearby sentry hut. She hefted a bronze horn and blew a signal blast that echoed across the valley. A moment later, a horn answered from Camp Jupiter. The Decumanian Gate swung open, and a mounted figure galloped up the road in their direction.

Nico grinned. He recognized that brown stallion, the rider's flowing purple cloak, her praetorian armor, her long dark curls.

He was glad he'd recovered from his shadow-travel, because he actually had the energy to run down the hill to meet her. "Hazel!" he cried.

Arion, her superfast steed, covered the distance between them in seconds. Hazel swung down from the saddle with the grace of a seasoned cowhand and ran to embrace Nico.

He buried his face in his sister's shoulder and held her tightly. She smelled of sweet, freshly turned earth.

Images flashed unbidden through his mind:

Bianca in the Lotus Hotel.

His mother gazing at him lovingly.

Apollo outside the Big House.

He pulled away and discovered Grief sitting on his shoulder, its tiny appendages stretching toward Hazel as if it, too, wanted a hug. Arion whinnied in alarm. Hazel gasped and stepped back, her hand closing around the hilt of her spatha. "Nico, what is that?"

"It's okay!" Nico told her. "They're with me!"

She kept her grip on her cavalry sword. "They?"

The rest of the cacodemons came tumbling down the hill, followed by Will, Yazan, and Savannah.

"Hazel!" Will beamed like he was having the best day of his life. "Nice to see you again! Say hello to the Cocoa Puffs."

The cacodemons formed a bouncing, yipping semicircle of fuzzy darkness at her feet.

She took her hand off her sword hilt and knelt like she was about to pet a cute dog. "The Cocoa Puffs? Oh my gods, they're adorable! What exactly are they?"

"That's a long story," said Nico. "I can tell you la—"

She extended one finger toward the single-eyed, urchin-like Puff.

"Wait!" Nico said.

Too late. She touched the top of its...head? Body? Nico wasn't sure because Loneliness's whole body was its head. It didn't matter. Hazel's face went blank. Tears sprang to her eyes.

Nico scooped up Loneliness. More images flooded his mind—his days alone inside a giant bronze jar, his time wandering the dark corridors of the Labyrinth—but he was braced for them. He put the Cocoa Puff aside and turned to Hazel. "Sorry about that."

She wiped her eyes. "What...what just happened? I was back in the Fields of Asphodel."

"The cacodemons can trigger your memories," explained Nico. "While we were in Tartarus, a very old god created them from my psyche. They're basically personifications of my emotions."

Hazel blinked. "I've heard and seen a lot of things as a demigod, but cacodemons?" She shook her head. "I guess there are still new things to learn in this world."

"We're still learning about them too," Will said. "They seem to be reaching out to other people more often now. We think it's their way of communicating."

Next to Nico, Yazan shifted nervously. "I'm sorry, Praetor. Perhaps I shouldn't have allowed the demons in."

"No, it's fine." Hazel managed a smile. "My brother is welcome, and so are his personified emotions. Yazan, Savannah, you've done a good job. You may return to guard duty. And, Arion, thank you, my friend. I can walk back."

The horse nuzzled the side of Hazel's head, messing up her hair with a sloppy kiss. Then he disappeared in a cloud of dust.

Yazan hesitated. Maybe he was curious to see what would happen next. But Savannah grabbed his wrist. With a respectful nod to Hazel, and one last suspicious look at Nico, she led Yazan back up the road to the tunnel.

"Those two are new here," Hazel explained. "Yazan's father is Vesper, the god of dusk. Savannah is a legacy. Third generation. She's, um, had a particularly hard time."

Nico filed that away to ask about later. Demigods all tended to have rough lives, at least until they grew into adulthood, got fully trained, and learned to survive in the mortal world. If Hazel made a point of saying Savannah's life had been particularly hard...it must've been bad indeed.

At the moment, though, he had more burning concerns.

"So, now that we're here," he said, "can you tell us what's going on?"

Hazel grimaced. She looked suddenly weary, as she had on yesterday's Iris-message. "I think it's best if I just show you. Come on."

As they crossed the footbridge over the Little Tiber, Will peppered Hazel with questions: How was Frank, her boyfriend and co-praetor? How had they managed to repair Camp Jupiter so quickly after the Battle of San Francisco Bay? What was her favorite meal in the mess hall?

Hazel laughed. "Wow, I've missed you, Will. I always feel so much more interesting in your presence."

"Good," he said. "Because I want to know everything."

She squeezed his arm. "You might regret saying that. Because what I'm about to show you is a lot." She nodded at the guards at the Decumanian Gate, and led them into the camp.

Nico's heart began to race—partly because it had been so long since he'd been here, and partly because Hazel was being so cryptic. It wasn't like her to withhold information.

Demigods in purple shirts crowded the Via Principalis. Some were offduty, heading to baths or standing in line for coffee at the kiosk of Bombilo, the two-headed barista. A couple of legionnaires were scrubbing graffiti off a barracks wall, a sight that Nico found very strange. Graffiti was a major breach of army discipline. Stranger still, the white paint read NON INIMICOS LICET—Latin for No enemies allowed. Why would someone write that in the middle of camp?

Will didn't seem fazed by anything until he saw his first Lar.

Floating toward them was a ghostly purple apparition—an older man in a toga and sandals. When he saw Will, his face turned livid. "Graecus!" he shouted. "Kill the graecus!"

"Theo," Hazel chided the ghost, "we've talked about this. The Greek campers are not our enemies anymore. Will is our guest."

"Hmph." Theo sneered. "Back in my day..."

He turned and floated away, grumbling in Latin.

"Sorry about that," Hazel told Will. "Ancestral spirits. Most of the Lares are nicer than Theo."

"Fascinating," Will said. "And I thought it was weird that we have a dragon."

"Oh, there's much more to come," Hazel warned.

She led them south, away from the headquarters and shops. Nico smelled the stables before they reached them. Then he got a whiff of the latrines. Gross, he thought. Most of Tartarus hadn't smelled that bad.

There, in the back corner of camp, stood the last barracks. It looked like all the others—a sturdy wooden structure, freshly painted and wellmaintained, but the smells from the neighborhood definitely made it the least desirable location to bunk.

Hazel walked up to the door and put her hand on it.

"The Fifth Cohort," she said. "My old home."

Nico nodded. "Didn't Percy stay here, too?"

"Yeah. And Jason. And Frank."

"All the best people," Will observed.

Hazel winced. "Most legionnaires would disagree. Historically, the Fifth Cohort has been for the demigods who didn't fit in. It has a terrible reputation."

"So...this is where we'll be staying, then?" Will guessed.

Hazel seemed lost in thought. It took her a moment to answer. "No. I'll show you your accommodations later. I brought you here because the Fifth is on patrol in the hills this morning. I figured it was the best place for him to wait."

Nico's insides started to form a knot. "Who is him?"

"I need you both to trust me," Hazel said.

"Of course," Will said.

"Why wouldn't we?" Nico added. "Also...who is him?"

The ground rumbled beneath Nico's feet, and tiny cracks appeared in the dirt. Skeletal fingertips began wriggling upward like earthworms escaping a flood. Without meaning to do it, he had started to raise the dead.

Will put a calming hand on his shoulder, and Nico relaxed. The dirt stopped trembling. The cracks closed.

Hazel kept her eyes fixed on the door of the barracks. "Just...promise me you won't freak out."

Nico nodded, though he was totally freaking out.

"Okay." Hazel took a deep breath. She looked terrified. "Come on in."

She pushed through the doorway and Nico followed. It took his eyes a moment to adjust from the brightness of the morning. Rows of tidy bunk beds lined the walls. In the shadows at the far end of the room, sitting on a footlocker, was a figure that Nico's mind couldn't quite process.

Humanoid...sort of, but this guy was way too big to be human. He looked like a bodybuilder who had swallowed three other bodybuilders. And from the shoulders up...Nico's first thought was that the guy was wearing a massive, exaggerated papier-mâché head, like the cabezudos he'd once seen at a Puerto Rican festival.

Will pushed in behind him. "What is it? Who— Oh..." His voice died as the creature rose to its feet. Its head nearly scraped the ceiling. It filled the space so impossibly that Nico forgot his promise to stay calm. His hand drifted to the pommel of his Stygian iron sword.

"Nico, stop!" Hazel gripped his wrist. "I can explain!"

He watched in horror as the creature stepped forward. It wore nothing but a blue cloth wrapped around its torso—a bath towel? A kilt? Thick fur covered its upper body, which was so bulked-up the creature could probably have bench-pressed the Statue of Liberty. Nico's gaze traveled up to its bovine snout, the golden ring piercing its nostrils, the massive brown eyes, and the curved white horns that tapered to deadly points.

Nico was vaguely aware of the Cocoa Puffs dancing in a panic around his feet, yipping Nope! Yikes! Nope! At his side, Will sputtered, his mouth seemingly unable to form words.

"Hazel," Nico said at last, "is that the Minotaur?"