'A daughter of Athena.' Annabeth's voice sounded brave though how she did it, Percy didn't know. 'I didn't walk halfway across Tartarus to be told what's impossible by some minor G.o.ddess.'

The dust quivered at their feet. Fog swirled around them with a sound like agonized wailing.

'Minor G.o.ddess?' Akhlys's gnarled fingernails dug into Hercules's shield, gouging the metal. 'I was old before the t.i.tans were born, you ignorant girl. I was old when Gaia first woke. Misery is eternal. Existence is misery. I was born of the eldest ones of Chaos and Night. I was '

'Yes, yes,' Annabeth said. 'Sadness and misery, blah blah blah. But you still don't have enough power to hide two demiG.o.ds with your Death Mist. Like I said: useless.'

Percy cleared his throat. 'Uh, Annabeth '

She flashed him a warning look: Work with me. He realized how terrified she was, but she had no choice. This was their best shot at stirring the G.o.ddess into action.

'I mean ... Annabeth is right!' Percy volunteered. 'Bob brought us all this way because he thought you could help. But I guess you're too busy staring at that shield and crying. I can't blame you. It looks just like you.'

Akhlys wailed and glared at the t.i.tan. 'Why did you inflict these annoying children on me?'

Bob made a sound somewhere between a rumble and a whimper. 'I thought I thought '

'The Death Mist is not for helping!' Akhlys shrieked. 'It shrouds mortals in misery as their souls pa.s.s into the Underworld. It is the very breath of Tartarus, of death, of despair!'

'Awesome,' Percy said. 'Could we get two orders of that to go?'

Akhlys hissed. 'Ask me for a more sensible gift. I am also the G.o.ddess of poisons. I could give you death thousands of ways to die less painful than the one you have chosen by marching into the heart of the pit.'

Around the G.o.ddess, flowers bloomed in the dust dark purple, orange and red blossoms that smelled sickly sweet. Percy's head swam.

'Nightshade,' Akhlys offered. 'Hemlock. Belladonna, henbane or strychnine. I can dissolve your innards, boil your blood.'

'That's very nice of you,' Percy said. 'But I've had enough poison for one trip. Now, can you hide us in your Death Mist, or not?'

'Yeah, it'll be fun,' Annabeth said.

The G.o.ddess's eyes narrowed. 'Fun?'

'Sure,' Annabeth promised. 'If we fail, think how great it will be for you, gloating over our spirits when we die in agony. You'll get to say I told you so for eternity.'

'Or, if we succeed,' Percy added, 'think of all the suffering you'll bring to the monsters down here. We intend to seal the Doors of Death. That's going to cause a lot of wailing and moaning.'

Akhlys considered. 'I enjoy suffering. Wailing is also good.'

'Then it's settled,' Percy said. 'Make us invisible.'

Akhlys struggled to her feet. The shield of Hercules rolled away and wobbled to a stop in a patch of poison flowers. 'It is not so simple,' the G.o.ddess said. 'The Death Mist comes at the moment you are closest to your end. Your eyes will be clouded only then. The world will fade.'

Percy's mouth felt dry. 'Okay. But ... we'll be shrouded from the monsters?'

'Oh, yes,' Akhlys said. 'If you survive the process, you will be able to pa.s.s unnoticed among the armies of Tartarus. It is hopeless, of course, but if you are determined, then come. I will show you the way.'

'The way to where, exactly?' Annabeth asked.

The G.o.ddess was already shuffling into the gloom.

Percy turned to look at Bob, but the t.i.tan was gone. How does a ten-foot-tall silver dude with a very loud kitten disappear?

'Hey!' Percy yelled to Akhlys. 'Where's our friend?'

'He cannot take this path,' the G.o.ddess called back. 'He is not mortal. Come, little fools. Come, experience the Death Mist.'

Annabeth exhaled and grabbed his hand. 'Well ... how bad can it be?'

The question was so ridiculous Percy laughed, even though it hurt his lungs. 'Yeah. Next date, though dinner in New Rome.'

They followed the G.o.ddess's dusty footprints through the poison flowers, deeper into the fog.

XLVII.

PERCY.

PERCY MISSED BOB.

He'd got used to having the t.i.tan on his side, lighting their way with his silver hair and his fearsome war broom.

Now their only guide was an emaciated corpse lady with serious self-esteem issues.

As they struggled across the dusty plain, the fog became so thick that Percy had to resist the urge to swat it away with his hands. The only reason he was able to follow Akhlys's path was because poisonous plants sprang up wherever she walked.

If they were still on the body of Tartarus, Percy figured they must be on the bottom of his foot a rough, calloused expanse where only the most disgusting plant life grew.

Finally they arrived at the end of the big toe. At least that's what it looked like to Percy. The fog dissipated, and they found themselves on a peninsula that jutted out over a pitch-black void.

'Here we are.' Akhlys turned and leered at them. Blood from her cheeks dripped on her dress. Her sickly eyes looked moist and swollen but somehow excited. Can Misery look excited?

'Uh ... great,' Percy asked. 'Where is here?'

'The verge of final death,' Akhlys said. 'Where Night meets the void below Tartarus.'

Annabeth inched forward and peered over the cliff. 'I thought there was nothing below Tartarus.'

'Oh, certainly there is ...' Akhlys coughed. 'Even Tartarus had to rise from somewhere. This is the edge of the earliest darkness, which was my mother. Below lies the realm of Chaos, my father. Here, you are closer to nothingness than any mortal has ever been. Can you not feel it?'

Percy knew what she meant. The void seemed to be pulling at him, leaching the breath from his lungs and the oxygen from his blood. He looked at Annabeth and saw that her lips were tinged blue.

'We can't stay here,' he said.

'No, indeed!' Akhlys said. 'Don't you feel the Death Mist? Even now, you pa.s.s between. Look!'

White smoke gathered around Percy's feet. As it coiled up his legs, he realized the smoke wasn't surrounding him. It was coming from him. His whole body was dissolving. He held up his hands and found they were fuzzy and indistinct. He couldn't even tell how many fingers he had. Hopefully still ten.

He turned to Annabeth and stifled a yelp. 'You're uh '

He couldn't say it. She looked dead.

Her skin was sallow, her eye sockets dark and sunken. Her beautiful hair had dried into a skein of cobwebs. She looked like she'd been stuck in a cool, dark mausoleum for decades, slowly withering into a desiccated husk. When she turned to look at him, her features momentarily blurred into mist.

Percy's blood moved like sap in his veins.

For years, he had worried about Annabeth dying. When you're a demiG.o.d, that goes with the territory. Most half-bloods don't live long. You always knew that the next monster you fought could be your last. But seeing Annabeth like this was too painful. He'd rather stand in the River Phlegethon, or get attacked by arai, or be trampled by giants.

'Oh, G.o.ds,' Annabeth sobbed. 'Percy, the way you look ...'

Percy studied his arms. All he saw were blobs of white mist, but he guessed that to Annabeth he looked like a corpse. He took a few steps, though it was difficult. His body felt insubstantial, like he was made of helium and cotton candy.

'I've looked better,' he decided. 'I can't move very well. But I'm all right.'

Akhlys clucked. 'Oh, you're definitely not all right.'

Percy frowned. 'But we'll pa.s.s unseen now? We can get to the Doors of Death?'

'Well, perhaps you could,' the G.o.ddess said, 'if you lived that long, which you won't.'

Akhlys spread her gnarled fingers. More plants bloomed along the edge of the pit hemlock, nightshade and oleander spreading towards Percy's feet like a deadly carpet. 'The Death Mist is not simply a disguise, you see. It is a state of being. I could not bring you this gift unless death followed true death.'

'It's a trap,' Annabeth said.

The G.o.ddess cackled. 'Didn't you expect me to betray you?'

'Yes,' Annabeth and Percy said together.

'Well, then, it was hardly a trap! More of an inevitability. Misery is inevitable. Pain is '

'Yeah, yeah,' Percy growled. 'Let's get to the fighting.'

He drew Riptide, but the blade was made of smoke. When he slashed at Akhlys, the sword just floated across her like a gentle breeze.

The G.o.ddess's ruined mouth split into a grin. 'Did I forget to mention? You are only mist now a shadow before death. Perhaps if you had time, you could learn to control your new form. But you do not have time. Since you cannot touch me, I fear any fight with Misery will be quite one-sided.'

Her fingernails grew into talons. Her jaw unhinged, and her yellow teeth elongated into fangs.

XLVIII.

PERCY.

AKHLYS LUNGED AT PERCY, and for a split second he thought: Well, hey, I'm just smoke. She can't touch me, right?

He imagined the Fates up in Olympus, laughing at his wishful thinking: LOL, NOOB!

The G.o.ddess's claws raked across his chest and stung like boiling water.

Percy stumbled backwards, but he wasn't used to being smoky. His legs moved too slowly. His arms felt like tissue paper. In desperation, he threw his backpack at her, thinking maybe it would turn solid when it left his hand, but no such luck. It fell with a soft thud.

Akhlys snarled, crouching to spring. She would have bitten Percy's face off if Annabeth hadn't charged and screamed HEY! right in the G.o.ddess's ear.

Akhlys flinched, turning towards the sound.

She lashed out at Annabeth, but Annabeth was better at moving than Percy. Maybe she wasn't feeling as smoky, or maybe she'd just had more combat training. She'd been at Camp Half-Blood since she was seven. Probably she'd had cla.s.ses Percy never got, like How to Fight While Partially Made of Smoke.

Annabeth dived straight between the G.o.ddess's legs and somersaulted to her feet. Akhlys turned and attacked, but Annabeth dodged again, like a matador.

Percy was so stunned he lost a few precious seconds. He stared at corpse Annabeth, shrouded in mist but moving as fast and confidently as ever. Then it occurred to him why she was doing this: to buy them time. Which meant Percy needed to help.

He thought furiously, trying to come up with a way to defeat Misery. How could he fight when he couldn't touch anything?

On Akhlys's third attack, Annabeth wasn't so lucky. She tried to veer aside, but the G.o.ddess grabbed Annabeth's wrist and pulled her hard, sending her sprawling.

Before the G.o.ddess could pounce, Percy advanced, yelling and waving his sword. He still felt about as solid as a Kleenex, but his anger seemed to help him move faster.

'Hey, Happy!' he yelled.

Akhlys spun, dropping Annabeth's arm. 'Happy?' she demanded.

'Yeah!' He ducked as she swiped at his head. 'You're downright cheerful!'

'Arggh!' She lunged again, but she was off-balance. Percy sidestepped and backed away, leading the G.o.ddess further from Annabeth.

'Pleasant!' he called. 'Delightful!'