BRIAR NEEDED A miracle, not a bedtime story. But right then, standing in shock as black water poured in around her legs, she recalled the legend Achelous had mentioned — the story of the flood.

Not the Noah story, but the Cherokee version that Piper told her when they were being insomniacs at the same time, with dancing ghosts and a skeleton dog.

It wasn't a rare event for them to be up at the same time in the middle of the night — what with demigod nightmares, trauma, and being too adrenaline-wired from war games.

Sometimes they'd talk about their dreams. Sometimes it hurt too much in the moment. Sometimes they'd talk for hours about anything and everything.

That day was a mixture of the latter two.

Briar had woken up because she'd heard whimpering. She frowned, wondering what was making that sound.

Every time, she thought that. Every time, she'd look sideways and realize.

Briar was accustomed to this routine by now. She flung her legs out of her bed, nearly tripped over her sheets, ran over to Piper's bed, knelt at the edge of it, and reached out to shake her sister. "Piper, Piper, Piper, wake up!"

Piper gasped, sitting up in her bed, drawing her knees to her chest and breathing heavily. Briar's hand retracted, not enough to swing by her side, but enough so it wasn't touching Piper. Briar went through the routine of making sure that Piper's breaths went normal, and her heartbeat slowed down.

Once that happened, Briar pulled her hand back to her side. "Is this a talk about it night?" she whispered.

"No," Piper croaked.

"Is this a talk about anything and everything night?"

". . . Yes."

"So, how bad were those losers in deathball, huh?"

So Briar hopped into Piper's bed, and they talked. They spent hours talking about everything and nothing until Piper brought up something new.

"Do you want me to tell you a story?" she asked, staring up at the ceiling.

Briar turned to look at her. "A Cherokee legend story?"

Piper nodded. "Yeah."

She'd told Briar a few Cherokee stories, but tapping into that part of her was hard for her. Briar understood. She didn't push Piper into doing anything she didn't want to do — unless it was something so ridiculously stupid, it was funny. "If you want," Briar answered.

"So," Piper started. "This man had a dog."

"I like dogs," Briar commented.

Piper rolled her eyes. "Obviously. You'd die for an angry dog before you'd die for me."

"That's not true. Well, maybe it is."

"I'm always right. Anyway, some dude had a dog. Every day the man took his dog to the edge of the lake to get water, and the dog would bark furiously at the lake, like he was mad at it."

"Bark bark," Briar offered helpfully. Without looking, Piper hit her in the face. "Ow! You hit my fucking nose!"

"Shut up," Piper commanded, and Briar shut her mouth. "Finally the man got very annoyed with his dog for barking so much, and he scolded it. 'Bad dog! Stop barking at the water. It's only water!' To his surprise, the dog looked right at him and began to talk."

"What is this, Spy Kids?" Briar muttered.

"We should watch that again," Piper commented. "Anyway, the dog said, 'One day soon, the storms will come. The waters will rise, and everyone will drown. You can save yourself and your family by building a raft, but first you will need to sacrifice me. You must throw me into the water.'"

Briar grimaced, but she'd heard enough of these stories from Piper to know that the lesson was coming up.

"The man thought the dog was lying — I mean, once he got over the shock that his dog could talk. When he protested, the dog said, 'If you don't believe me, look at the scruff of my neck. I am already dead.' The man grabbed the dog by the scruff of its neck and saw that its skin and fur were already coming apart. Underneath was nothing but bones. The dog was a skeleton dog."

"Ugh," Briar turned away. "You're literally going to make me throw up."

Piper patted her back. "Don't do it on my bed. So, with tears in his eyes, the man said good-bye to his annoying skeleton dog and tossed it into the water, where it promptly sank. The man built a raft, and when the flood came, he and his family survived."

"Without the stupid dog," Briar muttered.

"Yeah. Without the stupid dog. When the rains subsided, and the raft landed, the man and his family were the only ones alive. The man heard sounds from the other side of a hill — like thousands of people laughing and dancing — but when he raced to the top, alas, down below he saw nothing except bones littering the ground — thousands of skeletons of all the people who had died in the flood. He realized the ghosts of the dead had been dancing. That was the sound he heard. The end."

Briar rolled over to look at her sister. "I'll never look at Aurum and Argentum the same."

Piper smirked at her. "I've never looked at them as they were. Now, what's up with you and your totally-not-crush?"

Now, in the nymphaeum in Rome, as the dark water rose to her waist, Briar wondered why the river god Achelous had mentioned that story.

She wished she had a raft, but she feared she was more like the skeleton dog. She was already dead.

* * *

The basin filled with alarming speed. Briar, Reyna, Jason, and Percy pounded on the walls, looking for an exit, but they found nothing. They climbed into the alcoves to gain some height, but with water pouring out of each niche, it was like trying to balance at the edge of a waterfall. Even as Briar stood in a niche, the water was soon up to her knees. From the floor, it was probably eight feet deep and rising fast.

"I could try lightning," Jason said. "Maybe blast a hole in the roof?"

"That could bring down the whole room and crush us," Reyna said.

"Or electrocute us," Percy added.

"Not many choices," Jason said.

"Let me search the bottom," Percy said. "If this place was built as a fountain, there has to be a way to drain the thing. You guys, check the niches for secret exits. Maybe the seashells are knobs, or something." It was a desperate idea, but Briar was glad for something to do.

Percy jumped in the water. Reyna, Jason, and Briar climbed from niche to niche, kicking and pounding, wiggling seashells embedded in the stone; but they had no luck.

Sooner than Briar expected, Percy broke the surface, gasping and flailing. She offered her hand, and he almost pulled her in before she could help him up.

"Couldn't breathe," he choked. "The water . . . not normal. Hardly made it back."

The life force of the nymphs, Briar thought. It was so poisoned and malicious, even a son of the sea god couldn't control it.

As the water rose around her, Briar felt it affecting her too. Her leg muscles trembled like she'd been running for miles. Her hands turned wrinkled and dry, despite being in the middle of a fountain.

The others moved sluggishly. Jason's face was pale. He seemed to be having trouble holding his sword. Percy was drenched and shivering. His hair didn't look quite so dark, as if the color was leaching out. Reyna sheathed her sword as if she couldn't hold it anymore. Her hair and skin seemed to pale, which wasn't good.

"They're taking our power," Briar said. "Draining us."

"Jason," Percy coughed, "do the lightning."

Jason raised his sword. The room rumbled, but no lightning appeared. The roof didn't break. Instead, a miniature rainstorm formed at the top of the chamber. Rain poured down, filling the fountain even faster, but it wasn't normal rain. The stuff was just as dark as the water in the pool. Every drop stung Briar's skin.

"Not what I wanted," Jason said.

The water was up to their necks now. Briar could feel her strength fading.

"We'll survive," she murmured to herself, but she couldn't charmspeak her way out of this. Soon the poisonous water would be over their heads. They'd have to swim, and this stuff was already paralyzing them.

They would drown, just like in the visions she'd seen.

Percy started pushing the water away with the back of his hand, like he was shooing a bad dog. "Can't — can't control it!"

You will need to sacrifice me, the skeleton dog had said in the story. You must throw me into the water.

Briar felt like someone had grabbed the scruff of her neck and exposed the bones. She clutched her cornucopia.

"We can't fight this," she realized. "If we hold back, that just makes us weaker."

"What do you mean?" Jason shouted over the rain.

The water was up to their chins. Another few inches, and they'd have to swim. But the water wasn't halfway to the ceiling yet. Briar hoped that meant that they still had time.

"The horn of plenty," she said. "We have to overwhelm the nymphs with fresh water, give them more than they can use. If we can dilute this poisonous stuff—"

"Can your horn do that?" Percy struggled to keep his head above water, which was obviously a new experience for him. He looked scared out of his mind.

"Only with your help." Briar was beginning to understand how the horn worked. The good stuff it produced didn't come from nowhere. She'd only been able to bury Hercules in groceries when she'd let go of her anger and decided that negativity wouldn't pull her down.

To create enough clean fresh water to fill this room, she needed to go even deeper, tap her emotions even more. Unfortunately, she was losing her ability to focus. Did she even have that ability in the first place, though?

"I need you guys to channel everything you've got into the cornucopia," she said. "Percy, think about the sea."

"Salt water?"

"Doesn't matter! As long as it's clean. Jason, think about rainstorms — much more rain. Reyna, think about your strength, and lending it to someone. Hold the cornucopia."

They huddled together as the water lifted them off their ledges. Briar put one arm around Jason and Reyna and tried to keep them all afloat as they held the cornucopia between them.

Nothing happened. The rain came down in sheets, still dark and acidic.

Briar's legs felt like lead. The rising water swirled, threatening to pull her under. She could feel her strength fading.

"No good!" Jason yelled, spitting water.

"We're getting nowhere," Reyna agreed.

"You have to work together," Briar cried, hoping she was right. "Think of clean water — a storm of water. Don't hold anything back. Picture all your power, all your strength leaving you."

"That's not hard!" Percy said.

"But force it out!" Briar said. "Offer up everything, like — like you're already dead, and your only goal is to help the nymphs. It's got to be a gift . . . a sacrifice."

They got quiet at that word.

"Let's try again," Reyna said. "Together."

This time Briar bent all her concentration toward the horn of plenty as well. The nymphs wanted her youth, her life, her voice? Fine. She gave it up willingly and imagined all of her power flooding out of her.

I'm already dead, she told herself, as calm as the stupid skeleton dog. This is the only way.

Clear water blasted from the horn with such force, it pushed them against the wall. The rain changed to a white torrent, so clean and cold, it made Briar gasp.

"It's working!" Jason cried.

"Too well," Percy said. "We're filling the room even faster!"

He was right. The water rose so quickly, the roof was now only a few feet away. Briar could've reached up and touched the miniature rain clouds.

"Don't stop!" she said. "We have to dilute the poison until the nymphs are cleansed."

"What if they can't be cleansed?" Reyna asked. "They've been down here turning evil for thousands of years."

"Just don't hold back," Briar said. "Give everything. Even if we go under—"

Her head hit the ceiling. The rainclouds dissipated and melted into the water. The horn of plenty kept blasting out a clean torrent.

Briar pulled Reyna closer and kissed her.

"I love you," Briar said. "More than anything else in the world."

Reyna opened her mouth to say something, but then they were underwater.

Briar held her breath. The current roared in her ears. Bubbles swirled around her. Light still rippled through the room, and she was surprised she could see it. Was the water getting clearer?

Her lungs were about to burst, but Briar poured her last energy into the cornucopia. Water continued to stream out, though there was no room for more. Would the walls crack under the pressure?

Briar's vision went dark.

She thought the roar in her ears was her own dying heartbeat. Then she realized the room was shaking. The water swirled faster. Briar felt herself sinking.

With her last strength, she kicked upward. Her head broke the surface and she gasped for breath. The cornucopia stopped. The water was draining almost as fast as it had filled the room.

Briar realized that Reyna, Percy, and Jason's faces were still underwater. She hoisted them up one by one. Instantly, Percy gulped and began to thrash, but Reyna and Jason were as lifeless as rag dolls.

Briar clung to Reyna. She yelled Reyna's name, shook her, and slapped her face. She barely noticed when all the water had drained away and left them on the damp floor.

"Reyna, Reyna, Reyna . . ." Briar tried desperately to think. Should she turn Reyna on her side? Slap her back?

"Briar," Percy said, "I can help."

He knelt next to her and touched Reyna's forehead. Water gushed from Reyna's mouth. Her eyes flew open, and she sat up.

"Bri, what . . ." Reyna asked, but then Percy went to do the same to Jason, who was lying nearby, and a clap of thunder pushed them back.

When Briar's vision cleared, she saw Jason sitting up, still gasping, but the color was coming back to his face.

"Sorry," he coughed. "Didn't mean to do that."

Briar glared at him while she wrapped her limbs around Reyna. "You probably ruined my hairstyle, you idiot."

"It was ruined when the water came in," Reyna leaned into Briar's embrace. "But you still look pretty."

Percy grinned, reaching out to slap Jason's back. "In case you're wondering, that was clean water in your lungs. I could make it come out with no problem."

"Thanks, man." Jason clasped Percy's hand weakly. "But I think Briar's the real hero. She saved us all."

Yes, she did, a voice echoed through the chamber.

The niches glowed. Nine figures appeared, but they were no longer withered creatures. They were young, beautiful nymphs in shimmering blue gowns, their glossy black curls pinned up with silver and gold brooches. Their eyes were gentle shades of blue and green.

As Briar watched, eight of the nymphs dissolved into vapor and floated upward. Only the nymph in the center remained.

"Hagno?" Briar asked.

The nymph smiled. "Yes, my dear. I didn't think such selflessness existed in mortals . . . especially in demigods. No offense."

Reyna got to her feet, dragging Briar up with her. "How could we take offense? You just tried to drown us and suck out our lives."

Hagno winced. "Sorry about that. I was not myself. But you have reminded me of the sun and the rain and the streams in the meadows. Percy and Jason, thanks to you, I remembered the sea and the sky. I am cleansed. Thank you, Reyna, for reminding me that strength has more meaning than just power. But mostly, thanks to Briar. She shared something even better than clear running water." Hagno turned to her. "You have a good nature, Briar. And I'm a nature spirit. I know what I'm talking about."

Hagno pointed to the other side of the room. The stairs to the surface reappeared. Directly underneath, a circular opening shimmered into existence, like a sewer pipe, just big enough to crawl through. Briar suspected this was how the water had drained out.

"You may return to the surface," Hagno said. "Or, if you insist, you may follow the waterway to the giants. But choose quickly, because both doors will fade soon after I am gone. That pipe connects to the old aqueduct line, which feeds both this nymphaeum and the hypogeum that the giants call home."

"Ugh." Percy pressed on his temples. "Please, no more complicated words."

"Oh, home is not a complicated word." Hagno sounded completely sincere. "I thought it was, but now you have unbound us from this place. My sisters have gone to seek new homes . . . a mountain stream, perhaps, or a lake in a meadow. I will follow them. I cannot wait to see the forests and grasslands again, and the clear running water."

"Uh," Percy said nervously, "things have changed up above in the last few thousand years."

"Nonsense," Hagno said. "How bad could it be? Pan would not allow nature to become tainted. I can't wait to see him, in fact."

Percy looked like he wanted to say something, but he stopped himself.

"Good luck, Hagno," Briar said. "And thank you."

The nymph smiled one last time and vaporized.

Briefly, the nymphaeum glowed with a softer light, like a full moon. Briar smelled exotic spices and blooming roses. She heard distant music and happy voices talking and laughing. She guessed she was hearing hundreds of years of parties and celebrations that had been held at this shrine in ancient times, as if the memories had been freed along with the spirits.

"What is that?" Reyna asked nervously.

Briar grabbed Reyna's hand. "The ghosts are dancing. Come on. We'd better go meet the giants."