"Good to know."

"Now recap the pen."

I touched the pen cap to the sword tip and instantly Riptide shrank to a ballpoint pen again. I tucked it in my pocket, a little nervous, because I was famous for losing pens at school.

"You can't," Chiron said.

"Can't what?"

"Lose the pen," he said. "It is enchanted. It will always reappear in your pocket. Try it."

I was wary, but I threw the pen as far as I could down the hill and watched it disappear in the grass.

"It may take a few moments," Chiron told me. "Now check your pocket."

Sure enough, the pen was there.

"Okay, that's extremely cool," I admitted. "But what if a mortal sees me pulling out a sword?"

Chiron smiled. "Mist is a powerful thing, Percy."

"Mist?"

"Yes. Read The Iliad. It's full of references to the stuff. Whenever divine or monstrous elements mix with the mortal world, they generate Mist, which obscures the vision of humans. You will see things just as they are, being a half-blood, but humans will interpret things quite differently. Remarkable, really, the lengths to which humans will go to fit things into their version of reality."

I put Riptide back in my pocket.

For the first time, the quest felt real. I was actually leaving Half-Blood Hill. I was heading west with no adult supervision, no backup plan, not even a cell phone. (Chiron said cell phones were traceable by monsters; if we used one, it would be worse than sending up a flare.) I had no weapon stronger than a sword to fight off monsters and reach the Land of the Dead.

"Chiron ..." I said. "When you say the gods are immortal... I mean, there was a time before them, right?"

"Four ages before them, actually. The Time of the Titans was the Fourth Age, sometimes called the Golden Age, which is definitely a misnomer. This, the time of Western civilization and the rule of Zeus, is the Fifth Age."

"So what was it like ... before the gods?"

Chiron pursed his lips. "Even I am not old enough to remember that, child, but I know it was a time of darkness and savagery for mortals. Kronos, the lord of the Titans, called his reign the Golden Age because men lived innocent and free of all knowledge. But that was mere propaganda. The Titan king cared nothing for your kind except as appetizers or a source of cheap entertainment. It was only in the early reign of Lord Zeus, when Prometheus the good Titan brought fire to mankind, that your species began to progress, and even then Prometheus was branded a radical thinker. Zeus punished him severely, as you may recall. Of course, eventually the gods warmed to humans, and Western civilization was born."

"But the gods can't die now, right? I mean, as long as Western civilization is alive, they're alive. So ... even if I failed, nothing could happen so bad it would mess up everything, right?"

Chiron gave me a melancholy smile. "No one knows how long the Age of the West will last, Percy. The gods are immortal, yes. But then, so were the Titans. They still exist, locked away in their various prisons, forced to endure endless pain and punishment, reduced in power, but still very much alive. May the Fates forbid that the gods should ever suffer such a doom, or that we should ever return to the darkness and chaos of the past. All we can do, child, is follow our destiny."

"Our destiny ... assuming we know what that is."

"Relax," Chiron told me. "Keep a clear head. And remember, you may be about to prevent the biggest war in human history."

"Relax," I said. "I'm very relaxed."

When I got to the bottom of the hill, I looked back. Under the pine tree that used to be Thalia, daughter of Zeus, Chiron was now standing in full horse-man form, holding his bow high in salute. Just your typical summer-camp send-off by your typical centaur.

* * *

Argus drove us out of the countryside and into western Long Island. It felt weird to be on a highway again, Annabeth and Grover sitting next to me as if we were normal carpoolers. After two weeks at Half-Blood Hill, the real world seemed like a fantasy. I found myself staring at every McDonald's, every kid in the back of his parents' car, every billboard and shopping mall.

"So far so good," I told Annabeth. "Ten miles and not a single monster."

She gave me an irritated look. "It's bad luck to talk that way, seaweed brain."

"Remind me again—why do you hate me so much?"

"I don't hate you."

"Could've fooled me."

She folded her cap of invisibility. "Look ... we're just not supposed to get along, okay? Our parents are rivals."

"Why?"

She sighed. "How many reasons do you want? One time my mom caught Poseidon with his girlfriend in Athena's temple, which is hugely disrespectful. Another time, Athena and Poseidon competed to be the patron god for the city of Athens. Your dad created some stupid saltwater spring for his gift. My mom created the olive tree. The people saw that her gift was better, so they named the city after her."

"They must really like olives."

"Oh, forget it."

"Now, if she'd invented pizza—that I could understand."

"I said, forget it!"

In the front seat, Argus smiled. He didn't say anything, but one blue eye on the back of his neck winked at me.

Traffic slowed us down in Queens. By the time we got into Manhattan it was sunset and starting to rain.

Argus dropped us at the Greyhound Station on the Upper East Side, not far from my mom and Gabe's apartment. Taped to a mailbox was a soggy flyer with my picture on it: HAVE YOU SEEN THIS BOY?

I ripped it down before Annabeth and Grover could notice.

Argus unloaded our bags, made sure we got our bus tickets, then drove away, the eye on the back of his hand opening to watch us as he pulled out of the parking lot.

I thought about how close I was to my old apartment. On a normal day, my mom would be home from the candy store by now. Smelly Gabe was probably up there right now, playing poker, not even missing her.

Grover shouldered his backpack. He gazed down the street in the direction I was looking. "You want to know why she married him, Percy?"

I stared at him. "Were you reading my mind or something?"

"Just your emotions." He shrugged. "Guess I forgot to tell you satyrs can do that. You were thinking about your mom and your stepdad, right?"

I nodded, wondering what else Grover might've forgotten to tell me.

"Your mom married Gabe for you," Grover told me. "You call him 'Smelly,' but you've got no idea. The guy has this aura…. Yuck. I can smell him from here. I can smell traces of him on you, and you haven't been near him for a week."

"Thanks," I said. "Where's the nearest shower?"

"You should be grateful, Percy. Your stepfather smells so repulsively human he could mask the presence of any demigod. As soon as I took a whiff inside his Camaro, I knew: Gabe has been covering your scent for years. If you hadn't lived with him every summer, you probably would've been found by monsters a long time ago. Your mom stayed with him to protect you. She was a smart lady. She must've loved you a lot to put up with that guy—if that makes you feel any better."

It didn't, but I forced myself not to show it. I'll see her again, I thought. She isn't gone.

I wondered if Grover could still read my emotions, mixed up as they were. I was glad he and Annabeth were with me, but I felt guilty that I hadn't been straight with them. I hadn't told them the real reason I'd said yes to this crazy quest.

The truth was, I didn't care about retrieving Zeus's lightning bolt, or saving the world, or even helping my father out of trouble. The more I thought about it, I resented Poseidon for never visiting me, never helping my mom, never even sending a lousy child-support check. He'd only claimed me because he needed a job done.

All I cared about was my mom. Hades had taken her unfairly, and Hades was going to give her back.

You will be betrayed by one who calls you a friend, the Oracle whispered in my mind. You will fail to save what matters most in the end.

Shut up, I told it.

The rain kept coming down.

We got restless waiting for the bus and decided to play some Hacky Sack with one of Grover's apples. Annabeth was unbelievable. She could bounce the apple off her knee, her elbow, her shoulder, whatever. I wasn't too bad myself.

The game ended when I tossed the apple toward Grover and it got too close to his mouth. In one mega goat bite, our Hacky Sack disappeared—core, stem, and all.

Grover blushed. He tried to apologize, but Annabeth and I were too busy cracking up.

Finally the bus came. As we stood in line to board, Grover started looking around, sniffing the air like he smelled his favorite school cafeteria delicacy—enchiladas.

"What is it?" I asked.

"I don't know," he said tensely. "Maybe it's nothing."

But I could tell it wasn't nothing. I started looking over my shoulder, too.

I was relieved when we finally got on board and found seats together in the back of the bus. We stowed our backpacks. Annabeth kept slapping her Yankees cap nervously against her thigh.

As the last passengers got on, Annabeth clamped her hand onto my knee. "Percy."

An old lady had just boarded the bus. She wore a crumpled velvet dress, lace gloves, and a shapeless orange-knit hat that shadowed her face, and she carried a big paisley purse. When she tilted her head up, her black eyes glittered, and my heart skipped a beat.

It was Mrs. Dodds. Older, more withered, but definitely the same evil face.

I scrunched down in my seat.

Behind her came two more old ladies: one in a green hat, one in a purple hat. Otherwise they looked exactly like Mrs. Dodds—same gnarled hands, paisley handbags, wrinkled velvet dresses. Triplet demon grandmothers.

They sat in the front row, right behind the driver. The two on the aisle crossed their legs over the walkway, making an X. It was casual enough, but it sent a clear message: nobody leaves.

The bus pulled out of the station, and we headed through the slick streets of Manhattan. "She didn't stay dead long," I said, trying to keep my voice from quivering. "I thought you said they could be dispelled for a lifetime."

"I said if you're lucky," Annabeth said. "You're obviously not."

"All three of them," Grover whimpered. "Di immortales!"

"It's okay," Annabeth said, obviously thinking hard. "The Furies. The three worst monsters from the Underworld. No problem. No problem. We'll just slip out the windows."

"They don't open," Grover moaned.

"A back exit?" she suggested.

There wasn't one. Even if there had been, it wouldn't have helped. By that time, we were on Ninth Avenue, heading for the Lincoln Tunnel.

"They won't attack us with witnesses around," I said. "Will they?"

"Mortals don't have good eyes," Annabeth reminded me. "Their brains can only process what they see through the Mist."

"They'll see three old ladies killing us, won't they?"

She thought about it. "Hard to say. But we can't count on mortals for help. Maybe an emergency exit in the roof ... ?"

We hit the Lincoln Tunnel, and the bus went dark except for the running lights down the aisle. It was eerily quiet without the sound of the rain.