The other quest was fruitless.

The boys reported, thoroughly disappointed, that they'd found nothing in the Civil War sub or elsewhere in the museum; just a few elderly tourists, a dozing security guard, and– when they tried to inspect the artifacts– a whole battalion of glowing zombies in gray uniforms. Frank had had no luck in controlling them. When Piper had Iris-messaged them, they'd already been running back to the ship.

Leo had been stressed as he told the story, and was now even more stress trying to keep the ship in one piece as Percy and Jason's combined storm guided them away from the Romans. Percy had spoken to a Nereid in Charleston Harbor that told them to seek help from Chiron's brothers– which of the many, they had no idea. Leo punched in the latitude and longitude and went back to steering.

Hazel surprisingly hadn't retreated into her cabin. She and Frank had moved off to the side to talk, and it was very quickly growing heated. The others stood close to Leo, Jason, and Percy, trying to be supportive with only their presence. Emilia used the darkness swallowing them to form a shield of dark energy over the deck, keeping them all from being pelted by the rain and brittle wind.

Coach Hedge finally pried Leo off of the steering wheel after two hours, once the sea calmed and the winds died– they were far enough away from Charleston and the boys were exhausted. Emilia guided him to take a seat, giving him a few crumbs of nectar for his stiff hands along with a full glass of water while Annabeth and Piper tended to Percy and Jason.

Hazel and Frank were still arguing– Emilia was surprised that Hazel's seasickness hadn't kicked in by now. They didn't quiet down until they saw Leo staring. Frank scowled as they met at the mast, "No sign of a pursuit."

"Or land," added Hazel. They were now in the middle of the ocean. Open sea in all directions, a course toward the Mare Nostrum, no one able to help them but themselves.

Leo glanced at Emilia as if not wanting to think about what this would mean. He cleared his throat and turned to Annabeth, "Did you find the map you wanted?"

Annabeth nodded, though visibly pale. "I'll have to study it. How far are we from those coordinates?"

"At top rowing speed, about an hour," said Leo. "Any idea what we're looking for?"

"No," she admitted. "Percy?"

He raised his head, green eyes bloodshot and droopy. "The Nereid said Chiron's brothers were there, and they'd want to hear about that aquarium in Atlanta. I don't know what she meant, but..." He paused, like he'd used up all his energy saying that much. "She also warned me to be careful. Keto is the mother of sea monsters and can still send her children after us. The Nereid said we should expect an attack."

"Wonderful," muttered Frank.

Jason tried to stand, but sank back against the mast, supported by Piper. "Can we get the ship aloft? If we could fly–"

"That'd be great," said Leo, "except Festus tells me the port aerial stabilizer got pulverized when the ship raked against the dock at Fort Sumter. It'll take some time to fix. Until then, we're not flying anywhere."

Percy flexed his shoulders and winced. "Fine with me. The sea is good."

"Speak for yourself," said Hazel, already a bit queasy. "We need to go fast. We've burned another day, and Nico only has three more left."

"We can do it," promised Leo.

"If we have an hour," offered Emilia, "we should rest. Percy and Jason, you two need a nap– you look like you're about to throw up and cry at the same time. You used all your strength for that... terrifying storm. Go to your cabins."

Annabeth and Piper agreed that this was a good idea. They guided them down with Frank's help, leaving Emilia, Hazel, and Leo alone with Coach Hedge. As soon as Coach Hedge burst into his own rendition of the Pokémon theme song (apparently now it was Gotta Kill 'Em All), Emilia excused herself and left Leo and Hazel on their own.

She passed out as soon as she hit her bed. An hour was plenty of time to rest in her dark little cocoon of a room. She vaguely registered someone– probably Annabeth– knocking on her door, but turned away from it with a light huff and let herself drift back into deep sleep.

It didn't last long– nice things never did. She was thrown out of the bed entirely as the ship gave a heave, the bell beginning to ring madly. She scrambled to her feet, rushing out of her cabin alongside Jason and Percy, who were just as groggy and confused.

On the deck, Coach Hedge was yelling. Leo was trying to grab the port rail as an enormous slimy pink catfish–with glassy dead eyes, a gaping toothless maw, and a forest of tentacles sprouting from each nostril– rammed into the ship, trying to turn it over.

"Shrimpzilla!" cried Percy sleepily.

"I don't think I ever want to eat seafood again," said Emilia uncomfortably, the sun blazing down on them yet again. With any luck, she only needed one good hit to chop the catfish-thing in half.

Frank had rushed to help Hazel up, Annabeth and Piper were stumbling to starboard, Jason was trying to remain upright to help Leo reach the controls. No one knew what was going on or what to even do.

"How did it get so close?!" shouted Annabeth, pulling herself up on one of the rail shields.

"I don't know!" snarled Hedge. He looked around for his bat, which had rolled across the quarterdeck.

"I'm stupid!" Leo scolded himself. "Stupid, stupid! I forgot the sonar!" The ship tilted farther to starboard. Either the monster was trying to give them a hug, or it was about to capsize them.

"Sonar?" demanded Hedge. "Pan's pipes, Valdez! Maybe if you hadn't been staring into Hazel's eyes, holding hands for so long—"

"What?" yelped Frank.

"It wasn't like that!" protested Hazel.

"It doesn't matter!" said Piper. "Jason, can you call some lightning?"

Jason struggled to his feet. "I—" He only managed to shake his head. Summoning the storm earlier had taken too much out of him.

"Percy!" called Annabeth. "Can you talk to that thing? Do you know what it is?"

The son of the sea god shook his head, clearly mystified. "Maybe it's just curious about the ship. Maybe—"

The monster's tendrils lashed across the deck so fast, no one could give a warning. One slammed Percy in the chest and sent him crashing down the steps. Another wrapped around Piper's legs and dragged her, screaming, toward the rail. Dozens more tendrils curled around the masts, encircling the crossbows and ripping down the rigging.

Emilia lunged to grab Piper before she could be thrown overboard. Jason started to cut at the tendrils with his sword, but they came back like hydras. Annabeth had launched herself into the forest of tentacles, dodging and stabbing to clear a path for Emilia to drag Piper back onto the main deck. Frank was firing arrows at the creature's body, but that only served to annoy the monster, who bellowed and rocked the ship.

"Everyone, duck!" yelled Emilia.

They dropped as she swiped her hands out, tugging at every shadow she could summon and flinging it right into the monster's eyes. Red and pink blood splattered out at them, and the monster roared, mouth wide open as it flailed and released the ship.

Leo threw a small green vial right into the mouth just as a swarm of tentacles flew out, tossing Leo, Hazel, and Frank completely overboard. There was a muffled explosion as the catfish closed its mouth, a green flash of light bursting inside the giant pink monster. The catfish sank suddenly, the ship tilting like a vacuum was trying to suck it underwater.

"LEO!" yelled Emilia, scrambling to the railing and seeing him nowhere. "Hazel– Frank– where did they go?!"

The catfish was gone and so were the three demigods. Percy scrambled back onto the deck, and immediately announced that he was going to search for them underwater. Annabeth, Coach Hedge, and Buford (now returned without laundry) were trying to repair the ship so it wouldn't sink. Jason flew around the rigging putting out fires from the second green explosion that lit up the sky just above the mainmast.

Piper and Emilia lingered at the edge, waiting to see if Percy would emerge with bodies they'd need to attend to. Nothing turned up. It had been too long– too many minutes had passed. If he hadn't found them by now, they surely had drowned.

Katoptris wasn't helping them, either. Each time Piper held the blade out, she shook her head, as if no location was becoming apparent. Emilia didn't know what else to do– she had no idea how to repair the ship and frankly, didn't think it would be useful to get in the way unless someone directly told her what to do. The most she managed was placing shadows over where the fires were, helping Jason remove the oxygen that fueled it. By then, the sun was setting fast, and there was no sign of their friends.

They tried to use the time for other things, too anxious to just sit still and wait. They sent a dream vision to Chiron once it was dark enough for Emilia to tap Annabeth and Piper in, telling Chiron about what happened at Fort Sumter. Annabeth delivered disturbing news about a conversation with Reyna, implying the Romans would turn their attention to Camp Half-Blood if they couldn't enact justice by hurting them.

Piper had even seen a vision of SUVs already racing north– they were running out of time for everything. The centaur's face seemed toa ge thirty years during the course of their conversation, but he assured them he would see to the defenses of the camp. Tyson, Mrs. O'Leary, and Ella had arrived safely. If necessary, Tyson could summon an army of Cyclopes to the camp's defense, and Ella was already working with Rachel Dare to compare prophecies and predict the future. The eight of them had a quest to focus on– he'd handle the rest.

Percy came back empty-handed, having scoured the seafloor and finding nothing. Emilia sank down against the mast, staring into the darkness none of them could see into, waiting for a sign of movement. Nothing came. By the time the sun rose, they were losing hope. They couldn't do full repairs without Leo, even if the Argo II wasn't in immediate danger of sinking.

Then, at last, three giant pink bubbles burst at the surface off the starboard bow, ejecting Frank, Hazel, and Leo. Emilia couldn't stop Piper from diving into the water. She paddled over to Leo, kissing him on the cheek.

"Miss me?" laughed Leo.

Piper immediately smacked his shoulder. "Where were you? How are you guys alive?"

"Long story," said Leo. A picnic basket bobbed to the surface next to him. "Want a brownie?"

Percy lifted his arms, raising them out of the water and to where Jason and Emilia waited with towels. Emilia fussed over Leo for almost fifteen minutes, trying to dry him off and making sure he had no visible injuries. He'd resorted to shoving a brownie into her mouth to stop her from asking for the tenth time if he was sure he was alright.

As soon as they'd changed into dry clothes (Frank had to borrow a pair of too-small pants from Jason), the crew all gathered at the quarterdeck for a celebratory breakfast– except for Coach Hedge, who grumbled that the atmosphere was getting too cuddly for his tastes and went below to hammerout some dents in the hull.

While Leo fussed over his helm controls, Hazel and Frank related the story of the fish-centaurs– Bythos and Aphros– and their training camp. They'd assured them safe and quick passage across the Atlantic without further interference from anything like the Skolopendra (one of Keto's monsters).

"Incredible," said Jason as they ate. "These are really good brownies."

"That's your only comment?" demanded Piper.

He looked surprised. "What? I heard the story. Fish-centaurs. Merpeople. Letter of intro to the Tiber River god. Got it. But these brownies—"

"I know," said Frank, his mouth full. "Try them with Esther's peach preserves." Hazel, Emilia, and Piper made faces as Jason tried it.

Percy, for his part, wanted to hear every detail about the aquatic camp. He kept coming back to one point: "They didn't want to meet me?"

"It wasn't that," said Hazel. "Just...undersea politics, I guess. The merpeople are territorial. The good news is they're taking care of that aquarium in Atlanta. And they'll help protect the Argo II as we cross the Atlantic."

Percy nodded absently. "But they didn't want to meet me?"

Annabeth swatted his arm. "Come on, Seaweed Brain! We've got other things to worry about."

"She's right," said Hazel. "After today, Nico has less than two days. The fish-centaurs said we have to rescue him. He's essential to the quest somehow." She looked around defensively, as if waiting for someone to argue. No one did.

"Nico must have information about the Doors of Death," said Piper. "We'll save him, Hazel. We can make it in time. Right, Leo?"

"What?" Leo tore his eyes away from the controls. "Oh, yeah. We should reach the Mediterranean tomorrow morning. Then spend the rest of that day sailing to Rome, or flying, if I can get the stabilizer fixed by then...."

Jason suddenly looked as though his brownie with peach preserves didn't taste so good. "Which will put us in Rome on the last possible day for Nico. Twenty-four hours to find him—at most."

Percy crossed his legs. "And that's only part of the problem. There's the Mark of Athena, too."

Annabeth didn't seem happy with the change of topic. She rested her hand on her backpack, which, since they'd left Charleston, she always seemed to have with her. She opened the bag and brought out a thin bronze disk the diameter of a donut. "This is the map that I found at Fort Sumter. It's..." She stopped abruptly, staring at the smooth bronze surface. "It's blank!"

Percy took it and examined both sides. "It wasn't like this earlier?"

"No! I was looking at it in my cabin and..." Annabeth muttered under her breath. "It must be like the Mark of Athena. I can only see it when I'm alone. It won't show itself to other demigods."

Frank scooted back like the disk might explode. "What did it have on it? And what is the Mark of Athena? I still don't get it."

Annabeth took the disk from Percy. She turned it in the sunlight, but it remained blank. "The map was hard to read, but it showed a spot on the Tiber River in Rome. I think that's where my quest starts...the path I've got to take to follow the Mark."

"Maybe that's where you meet the river god Tiberinus," said Piper. "But what is the Mark?"

"The coin," Annabeth murmured.

Percy frowned. "What coin?"

Annabeth dug into her pocket and brought out a silver drachma. "I've been carrying this ever since I saw my mom at Grand Central. It's an Athenian coin." She passed it around. Emilia rubbed it between her fingers when it was her turn, noticing an owl on an olive branch.

"What does that mean?" asked Emilia, gesturing to the letters 'ΑΘΕ.' "Alpha... theta... epsilon... does it mean something?"

"Of The Athenians," said Annabeth. "Or you could read it as the children of Athena. It's sort of the Athenian motto."

"Like SPQR for the Romans," guessed Piper.

Annabeth nodded. "Anyway, the Mark of Athena is an owl, just like that one. It appears in fiery red. I've seen it in my dreams. Then twice at Fort Sumter."

She described what had happened at the fort—the voice of Gaea, the spiders in the garrison, the Mark burning them away. She seemed to speak faster the further into the story she got, as if wanting it to be over. Clearly, it made her severely anxious.

Percy took Annabeth's hand. "I should have been there for you."

"But that's the point," said Annabeth. "No one can be there for me. When I get to Rome, I'll have to strike out on my own. Otherwise, the Mark won't appear. I'll have to follow it to...to the source."

Frank took the coin from Emilia. He stared at the owl. "The giants' bane stands gold and pale, Won with pain from a woven jail." He looked up at Annabeth. "What is it...this thing at the source?"

Before Annabeth could answer, Jason spoke up. "A statue. A statue of Athena. At least...that's my guess. I don't know for sure but the more I think about it... there's only one artifact that could fit the legend." He turned to Annabeth. "I'm sorry. I should have told you everything I've heard, much earlier. But honestly, I was scared. If this legend is true—"

"I know," said Annabeth. "I figured it out, Jason. I don't blame you. But if we manage to save the statue, Greek and Romans together...Don't you see? It could heal the rift."

"Hold on." Percy made a time-out gesture. "What statue?"

Annabeth took back the silver coin and slipped it into her pocket. "The Athena Parthenos. The most famous Greek statue of all time. It was forty feet tall, covered in ivory and gold. It stood in the middle of the Parthenon in Athens."

"Oh." Emilia had heard of this. "The one that disappeared... some suspected the Romans took it."

Jason nodded. "That's one theory, and it fits the legend I heard at Camp Jupiter. To break the Greeks' spirit, the Romans carted off the Athena Parthenos when they took over the city of Athens. They hid it in an underground shrine in Rome. The Roman demigods swore it would never see the light of day. They literally stole Athena, so she could no longer be the symbol of Greek military power. She became Minerva, a much tamer goddess."

"And the children of Athena have been searching for the statue ever since," said Annabeth. "Most don't know about the legend, but in each generation, a few are chosen by the goddess. They're given a coin like mine. They follow the Mark of Athena... a kind of magical trail that links them to the statue... hoping to find the resting place of the Athena Parthenos and get the statue back."

Percy hummed. "So if we— I mean you— find the statue...what would we do with it? Could we even move it?"

"I'm not sure," admitted Annabeth. "But if we could save it somehow, it could unite the two camps. It could heal my mother of this hatred she's got, tearing her two aspects apart. And maybe... maybe the statue has some sort of power that could help us against the giants."

"And you're supposed to do all this on your own?" said Emilia in disbelief. "That's like..." She decided not to say it was like trying to carry a mountain– it might ring too close to Annabeth having had to hold up the sky at one point. "The fate of demigods, their ability to cooperate, the hostility Gaea feeds off of... you're expected to fix all that without anyone's help?"

"I have to succeed," said Annabeth simply, giving her a look that reminded her of the day Emilia had told them about Rhea's task for her. A sadness, an understanding, a ferocity that showed she believed it was possible if someone had chosen them for this. "The risk is worth it."

Hazel twirled her hair pensively. "I don't like the idea of you risking your life alone, but you're right. We saw what recovering the golden eagle standard did for the Roman legion. If this statue is the most powerful symbol of Athena ever created—"

"It could kick some serious booty," offered Leo.

Hazel frowned. "That wasn't the way I'd put it, but yes."

"Except..." Percy took Annabeth's hand again. "No child of Athena has ever found it. Annabeth, what's down there? What's guarding it? If it's got to do with spiders—?"

"Won through pain from a woven jail," Frank recalled. "Woven, like webs?"

Annabeth's face turned as white as printer paper, as if she was trying to hold back a panic attack. "We'll deal with that when we get to Rome," Piper suggested soothingly. "It's going to work out. Annabeth is going to kick some serious booty, too. You'll see."

"Yeah," Percy said. "I learned a long time ago: Never bet against Annabeth." Annabeth looked at them both gratefully.

In an attempt to lighten the mood, Leo pushed a button, and a loud blast of steam exploded from Festus's mouth, making everyone jump. "Well! Good pep rally, but there's still a ton of things to fix on this ship before we get to the Mediterranean. Please report to Supreme Commander Leo for your superfun list of chores!"

The ship continued to sail as they were divided up. Emilia was lucky to be assigned a job with Leo, moving supplies to certain locations and being told specifically what to do– it helped her be more productive. He even let her go to dinner early because she'd been a 'good little sailor.' She made sure to remind him that just because he'd almost been lost didn't mean he could get too comfortable giving her silly nicknames– she could still kick his ass if she chose to.

She took the food to her room and immediately set up an Iris-message with Hylla, hoping that she wouldn't be upset that she hadn't called the night before.

"Hey!" said Hylla immediately, having been waiting with nothing in her hands. Usually she was reading or trying to organize something. "I was worried."

"We thought we lost three of our friends last night," said Emilia honestly, shaking her head. "I couldn't bring myself to call. I was on the deck staring into the dark ocean for... the entire night."

"Are they alright?"

"Yes, everyone's okay. Annabeth told me she saw Reyna at Fort Sumter."

"Reyna told me, too. She's going to try to stall... but I've met Octavian and there's only so much she can do. I'll help where I can. Send obstacles their way, have Krista coordinate with Pollux to send reinforcements to Camp Half-Blood in the event that things go wrong. The best they can do is prepare."

Emilia nodded. "Yes, we've told them to get themselves ready. Gods... nothing was supposed to happen like this. I didn't expect this to be easy but it's one complication after another."

"I wish I was there," said Hylla quietly. "I keep having these dreams, I keep seeing you swallowed by darkness."

"I summon darkness," said Emilia. "Doesn't mean it will swallow me– it just looks like that."

"It feels like it does. I see you one moment then the next I can't... I call for you and I can't find you. Darkness so deep, a cold so brittle, a despair that doesn't end. I wish I had been chosen for this. I wish I didn't have to be so far when you're in danger. I hate feeling powerless."

Emilia motioned for her to close her eyes. "Go on, shut them. Bring yourself into darkness."

With a light and perhaps defiant huff, Hylla shut her eyes. "I want you to imagine a standard living room," said Emilia. "A dark one. Moonlight streaming in through a large window, the curtains parted. Two couches facing each other. Chairs between them on one side, and a blanket laid over it all to make a small fort in the middle. Inside the fort there is a pile of blankets, soft as a cloud. You find yourself lying inside the fort, barely able to see anything outside of it."

Hylla nodded, as if to prompt her into continuing. Emilia went on, "Now imagine I'm in there with you. Curled up in a ball, sound asleep. You reach out to touch my hand and I open my eyes, I smile at you. The room brightens, the sun rising and bathing everything– even the inside of the fort– in light. You have brought light into my life, Hylla. I can't be swallowed by darkness as long as I have you."

Hylla looked like she might cry. "You say that and I want to believe it but I know this dream is real."

"So is my dream. That I make it back to you. The unknown terrifies me, Hylla, it does. But I can still believe that we'll persevere. One day we'll have a moment just like that. We will both hold onto that hope and with that in mind, nothing will get in our way. Nothing will stop that from happening."

"Promise me," begged Hylla. "Promise me that you won't let the darkness take you."

Emilia hesitated. "I've learned not to make such specific promises. I can promise that I'll battle it if I have to. No being could chain me down, no darkness could ever take me from you. You said you'd wait for me and I will fight with everything I have in me to get back to you. That is my promise."

She got the sense that her words did little to console Hylla. As she laid in her bed after their call, she felt the room was colder than before. She wondered what the dream meant, whether it was just Hylla's fears or a premonition of what was to come. Her mother made no effort to appear even when she thought of summoning her, Eris did not come.

Where had she gone? Was she already back in Tartarus?

Or was she waiting for something?

-

A/N: Happy 400 pages! Was listening to Work Song by Hozier while writing this so that's the inspo for Emilia's words to Hylla :')