“Uh-huh.” Annabeth turned to Percy. “Well, it’s getting late. We should probably get lunch at one of those restaurants the tour guide recommended. Then we can find the Doors of Death.”

“Aha!” Nyx cried in triumph. Her brood of shadows stirred and echoed: “Aha! Aha!”

“You wish to see the Doors of Death?” Nyx asked. “They lie at the very heart of Tartarus. Mortals such as you could never reach them, except through the halls of my palace—the Mansion of Night!”

She gestured behind her. Floating in the abyss, maybe three hundred feet below, was a doorway of black marble, leading into some sort of large room.

Annabeth’s heart pounded so strongly she felt it in her toes. That was the way forward—but it was so far down, an impossible jump. If they missed, they would fall into Chaos and be scattered into nothingness—a final death with no do-over. Even if they could make the jump, the goddess of night and her most fearsome children stood in their way.

With a jolt, Annabeth realized what needed to happen. Like everything she’d ever done, it was a long shot. In a way, that calmed her down. A crazy idea in the face of death?

Okay, her body seemed to say, relaxing. This is familiar territory.

She managed a bored sigh. “I suppose we could do one picture, but a group shot won’t work. Nyx, how about one of you with your favorite child? Which one is that?”

The brood rustled. Dozens of horrible glowing eyes turned toward Nyx.

The goddess shifted uncomfortably, as if her chariot were heating up under her feet. Her shadow horses huffed and pawed at the void.

“My favorite child?” she asked. “All my children are terrifying!”

Percy snorted. “Seriously? I’ve met the Fates. I’ve met Thanatos. They weren’t so scary. You’ve got to have somebody in this crowd who’s worse than that.”

“The darkest,” Annabeth said. “The most like you.”

“I am the darkest,” hissed Eris. “Wars and strife! I have caused all manner of death!”

“I am darker still!” snarled Geras. “I dim the eyes and addle the brain. Every mortal fears old age!”

“Yeah, yeah,” Annabeth said, trying to ignore her chattering teeth. “I’m not seeing enough dark. I mean, you’re the children of Night! Show me dark!”

The horde of arai wailed, flapping their leathery wings and stirring up clouds of blackness. Geras spread his withered hands and dimmed the entire abyss. Eris breathed a shadowy spray of buckshot across the void.

“I am the darkest!” hissed one of the demons.

“No, I!”

“No! Behold my darkness!”

If a thousand giant octopuses had squirted ink at the same time, at the bottom of the deepest, most sunless ocean trench, it could not have been blacker. Annabeth might as well have been blind. She gripped Percy’s hand and steeled her nerves.

“Wait!” Nyx called, suddenly panicked. “I can’t see anything.”

“Yes!” shouted one of her children proudly. “I did that!”

“No, I did!”

“Fool, it was me!”

Dozens of voices argued in the darkness.

The horses whinnied in alarm.

“Stop it!” Nyx yelled. “Whose foot is that?”

“Eris is hitting me!” cried someone. “Mother, tell her to stop hitting me!”

“I did not!” yelled Eris. “Ouch!”

The sounds of scuffling got louder. If possible, the darkness became even deeper. Annabeth’s eyes dilated so much, they felt like they were being pulled out of their sockets.

She squeezed Percy’s hand. “Ready?”

“For what?” After a pause, he grunted unhappily. “Poseidon’s underpants, you can’t be serious.”

“Somebody give me light!” Nyx screamed. “Gah! I can’t believe I just said that!”

“It’s a trick!” Eris yelled. “The demigods are escaping!”

“I’ve got them,” screamed an arai.

“No, that’s my neck!” Geras gagged.

“Jump!” Annabeth told Percy.

They leaped into the darkness, aiming for the doorway far, far below.

AFTER THEIR FALL INTO TARTARUS, jumping three hundred feet to the Mansion of Night should have felt quick.

Instead, Annabeth’s heart seemed to slow down. Between the beats she had ample time to write her own obituary.

Annabeth Chase, died age 17.

BA-BOOM.

(Assuming her birthday, July 12, had passed while she was in Tartarus; but honestly, she had no idea.)

BA-BOOM.

Died of massive injuries while leaping like an idiot into the abyss of Chaos and splattering on the entry hall floor of Nyx’s mansion.

BA-BOOM.

Survived by her father, stepmother, and two stepbrothers who barely knew her.

BA-BOOM.

In lieu of flowers, please send donations to Camp Half-Blood, assuming Gaea hasn’t already destroyed it.

Her feet hit solid floor. Pain shot up her legs, but she stumbled forward and broke into a run, hauling Percy after her.

Above them in the dark, Nyx and her children scuffled and yelled, “I’ve got them! My foot! Stop it!”

Annabeth kept running. She couldn’t see anyway, so she closed her eyes. She used her other senses—listening for the echo of open spaces, feeling for cross-breezes against her face, sniffing for any scent of danger—smoke, or poison, or the stench of demons.

It wasn’t the first time she’d plunged through darkness. She imagined she was back in the tunnels under Rome, searching out the Athena Parthenos. In retrospect, her journey to Arachne’s cavern seemed like a trip to Disneyland.

The squabbling sounds of Nyx’s children got farther away. That was good. Percy was still running at her side, holding her hand. Also good.

In the distance ahead of them, Annabeth began to hear a throbbing sound, like her own heartbeat echoing back, amplified so powerfully, the floor vibrated underfoot. The sound filled her with dread, so she figured it must be the right way to go. She ran toward it.

As the beat got louder, she smelled smoke and heard the flickering of torches on either side. She guessed there would be light, but a crawling sensation across her neck warned her it would be a mistake to open her eyes.

“Don’t look,” she told Percy.

“Wasn’t planning on it,” he said. “You can feel that, right? We’re still in the Mansion of Night. I do not want to see it.”

Smart boy, Annabeth thought. She used to tease Percy for being dumb, but in truth his instincts were usually right on target.

Whatever horrors lay in the Mansion of Night, they weren’t meant for mortal eyes. Seeing them would be worse than staring at the face of Medusa. Better to run in darkness.

The throbbing got louder still, sending vibrations straight up Annabeth’s spine. It felt like someone was knocking on the bottom of the world, demanding to be let in. She sensed the walls opening up on either side of them. The air smelled fresher—or at least not quite as sulfurous. There was another sound, too, closer than the deep pulsing…the sound of flowing water.

Annabeth’s heart raced. She knew the exit was close. If they could make it out of the Mansion of Night, maybe they could leave the dark brood of demons behind.

She began to run faster, which would have meant her death if Percy hadn’t stopped her.

“ANNABETH!” PERCY PULLED HER BACK just as her foot hit the edge of a drop-off. She almost pitched forward into who-knew-what, but Percy grabbed her and wrapped her in his arms.

“It’s okay,” he promised.

She pressed her face into his shirt and kept her eyes closed tight. She was trembling, but not just from fear. Percy’s embrace was so warm and comforting she wanted to stay there forever, safe and protected…but that wasn’t reality. She couldn’t afford to relax. She couldn’t lean on Percy any more than she had to. He needed her, too.

“Thanks…” She gently disentangled herself from his arms. “Can you tell what’s in front of us?”

“Water,” he said. “I’m still not looking. I don’t think it’s safe yet.”

“Agreed.”

“I can sense a river…or maybe it’s a moat. It’s blocking our path, flowing left to right through a channel cut in the rock. The opposite side is about twenty feet away.”

Annabeth mentally scolded herself. She’d heard the flowing water, but she had never considered she might be running headlong into it.

“Is there a bridge, or—?”

“I don’t think so,” Percy said. “And there’s something wrong with the water. Listen.”

Annabeth concentrated. Within the roaring current, thousands of voices cried out—shrieking in agony, pleading for mercy.

Help! they groaned. It was an accident!

The pain! their voices wailed. Make it stop!

Annabeth didn’t need her eyes to visualize the river—a black briny current filled with tortured souls being swept deeper and deeper into Tartarus.

“The River Acheron,” she guessed. “The fifth river of the Underworld.”

“I liked the Phlegethon better than this,” Percy muttered.

“It’s the River of Pain. The ultimate punishment for the souls of the damned—murderers, especially.”

Murderers! the river wailed. Yes, like you!

Join us, another voice whispered. You are no better than we are.

Annabeth’s head was flooded with images of all the monsters she’d killed over the years.

That wasn’t murder, she protested. I was defending myself!

The river changed course through her mind—showing her Zoë Nightshade, who had been slain on Mount Tamalpais because she’d come to rescue Annabeth from the Titans.

She saw Nico’s sister, Bianca di Angelo, dying in the collapse of the metal giant Talos, because she also had tried to save Annabeth.

Michael Yew and Silena Beauregard…who had died in the Battle of Manhattan.

You could have prevented it, the river told Annabeth. You should have seen a better way.

Most painful of all: Luke Castellan. Annabeth remembered Luke’s blood on her dagger after he’d sacrificed himself to stop Kronos from destroying Olympus.

His blood is on your hands! the river wailed. There should have been another way!

Annabeth had wrestled with the same thought many times. She’d tried to convince herself Luke’s death wasn’t her fault. Luke had chosen his fate. Still…she didn’t know if his soul had found peace in the Underworld, or if he’d been reborn, or if he’d been washed into Tartarus because of his crimes. He might be one of the tortured voices flowing past right now.

You murdered him! the river cried. Jump in and share his punishment!

Percy gripped her arm. “Don’t listen.”

“But—”

“I know.” His voice sounded as brittle as ice. “They’re telling me the same stuff. I think…I think this moat must be the border of Night’s territory. If we get across, we should be okay. We’ll have to jump.”

“You said it was twenty feet!”