Set turned, and the look on his face was priceless. I raised my staff and wand, gathering my magic.

"Except that Horus is not alone," I said. "And we're not going to fight you in the desert."

I slammed my staff against the stones and shouted, "Washington, D.C.!"

The pyramid shook. For a moment, nothing else happened.

Set seemed to realize what I was doing. He let out a nervous laugh. "Magic one-oh-one, Sadie Kane. You can't open a portal during the Demon Days!"

"A mortal can't," I agreed. "But a G.o.ddess of magic can."

Above us, the air crackled with lightning. The top of the cavern dissolved into a churning vortex of sand as large as the pyramid.

Demons stopped fighting and looked up in horror. Magicians stammered midspell, their faces slack with awe.

The vortex was so powerful that it ripped blocks off the pyramid and sucked them into the sand. And then, like a giant lid, the portal began to descend.

"No!" Set roared. He blasted the portal with flames, then turned on me and hurled stones and lightning, but it was too late. The portal swallowed us all.

The world seemed to flip upside down. For a heartbeat, I wondered if I'd made a terrible miscalculation-if Set's pyramid would explode in the portal, and I'd spend eternity floating through the Duat as a billion little particles of Sadie sand. Then, with a sonic boom, we appeared in the cold morning air with a brilliant blue sky above us. Spread out below us were the snow-covered fields of the National Mall in Washington, D.C.

The red pyramid was still intact, but cracks had appeared on its surface. The gold capstone glowed, trying to maintain its magic, but we weren't in Phoenix anymore. The pyramid had been ripped from its source of power, the desert, and in front us loomed the default gateway for North America, the tall white obelisk that was the most powerful focal point of Ma'at on the continent: the Washington Monument.

Set screamed something at me in Ancient Egyptian. I was fairly sure it wasn't a compliment.

"I will rend your limbs from their sockets!" he shouted. "I will-"

"Die?" Carter suggested. He rose behind Set and swung his sword. The blade cut into Set's armor at the ribs-not a killing blow, but enough to knock the Red G.o.d off balance and send him tumbling down the side of his pyramid. Carter bounded after him, and in the Duat I could see arcs of white energy pulsing from the Washington Monument to the Horus avatar, charging it with new power.

"The book, Sadie!" Carter shouted as he ran. "Do it now!"

I must've been dazed from summoning the portal, because Set understood what Carter was saying a lot faster than I did.

"No!" the Red G.o.d shouted. He charged towards me, but Carter intercepted him halfway up the slope.

He grappled with Set, holding him back. The stones of the pyramid cracked and crumbled under the weight of their G.o.dly forms. All around the base of the pyramid, demons and magicians who'd been pulled through the portal and knocked momentarily unconscious were starting to stir.

The book, Sadie...Sometimes it's helpful to have someone other than yourself inside your head, because one can slap the other. Duh, the book!

I held out my hand and summoned the little blue tome we'd stolen from Paris: The Book of Overcoming Set. I unfolded the papyrus; the hieroglyphs were as clear as a nursery school primer. I called for the feather of truth, and instantly it appeared, glowing above the pages.

I began the spell, speaking the Divine Words, and my body rose into the air, hovering a few centimeters above the pyramid. I chanted the story of creation: the first mountain rising above the waters of chaos, the birth of the G.o.ds Ra, Geb, and Nut, the rise of Ma'at, and the first great empire of men, Egypt.

The Washington Monument began to glow as hieroglyphs appeared along its sides. The capstone gleamed silver.

Set tried to lash out at me, but Carter intercepted him. And the red pyramid began to break apart.

I thought about Amos and Zia, trapped inside under tons of stone, and I almost faltered, but my mother's voice spoke in my mind: Stay focused, dearest. Watch for your enemy.

Yes, Isis said. Destroy him!

But somehow I knew that wasn't what my mother meant. She was telling me to watch. Something important was about to happen.

Through the Duat, I saw magic forming around me, weaving a white sheen over the world, reinforcing Ma'at and expelling chaos. Carter and Set wrestled back and forth as huge chunks of the pyramid collapsed.

The feather of truth glowed, shining like a spotlight on the Red G.o.d. As I neared the end of the spell, my words began tearing Set's form to shreds.

In the Duat, his fiery whirlwind was being stripped away, revealing a black-skinned, slimy thing like an emaciated Set animal-the evil essence of the G.o.d. But in the mortal world, occupying the same s.p.a.ce, there stood a proud warrior in red armor, blazing with power and determined to fight to the death.

"I name you Set," I chanted. "I name you Evil Day."

With a thunderous roar, the pyramid imploded. Set fell crashing into the ruins. He tried to rise, but Carter swung his sword. Set barely had time to raise his staff. Their weapons crossed, and Horus slowly forced Set to one knee.

"Now, Sadie!" Carter yelled.

"You have been my enemy," I chanted, "and a curse on the land."

A line of white light shot down the length of the Washington Monument. It widened into a rift-a doorway between this world and the brilliant white abyss that would lock Set away, trapping his life force. Maybe not forever, but for a long, long time.

To complete the spell, I only had to speak one more line: "Deserving no mercy, an enemy of Ma'at, you are exiled beyond the earth."

The line had to be spoken with absolute conviction. The feather of truth required it. And why shouldn't I believe it? It was the truth. Set deserved no mercy. He was an enemy of Ma'at.

But I hesitated.

"Watch for your enemy," my mother had said.

I looked towards the top of the monument, and in the Duat I saw chunks of pyramid flying skyward and the souls of demons lifting off like fireworks. As Set's chaos magic dispersed, all the force that had been charging up, ready to destroy a continent, was being sucked into the clouds. And as I watched, the chaos tried to form a shape. It was like a red reflection of the Potomac-an enormous crimson river at least a mile long and a hundred meters wide. It writhed in the air, trying to become solid, and I felt its rage and bitterness. This was not what it had wanted. There was not enough power or chaos for its purpose. To form properly, it needed the death of millions, the wasting of an entire continent.

It was not a river. It was a snake.

"Sadie!" Carter yelled. "What are you waiting for?"

He couldn't see it, I realized. No one could but me.

Set was on his knees, writhing and cursing as white energy encircled him, pulling him towards the rift. "Lost your stomach, witch?" he bellowed. Then he glared at Carter. "You see, Horus? Isis was always a coward. She could never complete the deed!"

Carter looked at me, and for a moment I saw the doubt on his face. Horus would be urging him towards b.l.o.o.d.y vengeance. I was hesitating. This is what had turned Isis and Horus against each other before. I couldn't let it happen now.

But more than that, in Carter's wary expression I saw the way he used to look at me on our visiting days-when we were practically strangers, forced to spend time together, pretending we were a happy family because Dad expected it of us. I didn't want to go back to that. I wasn't pretending anymore. We were a family, and we had to work together.

"Carter, look." I threw the feather of truth into the sky, breaking the spell.

"No!" Carter screamed.

But the feather exploded into silver dust that clung to the form of the serpent, forcing it to become visible, just for an instant.

Carter's mouth fell open as the serpent writhed in the air above Washington, slowly losing power.

Next to me, a voice screamed: "Wretched G.o.ds!"

I turned to see Set's minion, Face of Horror, with his fangs bared and his grotesque face only inches from mine, a jagged knife raised above my head. I only had time to think: I'm dead, before a flash of metal registered in the corner of my eye. There was a sickening thud, and the demon froze.

Carter had thrown his sword with deadly accuracy. The demon dropped his knife, fell to his knees, and stared down at the blade that was now sheathed in his side.

He crumpled to his back, exhaling with an angry hiss. His black eyes fixed on me, and he spoke in a completely different voice-a rasping, dry sound, like a reptile's belly sc.r.a.ping over sand. "This is not over, G.o.dling. All this I have wrought with a wisp of my voice, the merest bit of my essence wriggling from my weakened cage. Imagine what I shall do when fully formed."

He gave me a ghastly smile, and then his face went slack. A tiny line of red mist curled from his mouth-like a worm or a fresh-hatched snake-and writhed upward into the sky to join its source. The demon's body disintegrated into sand.

I looked up once more at the giant red serpent slowly dissolving in the sky. Then I summoned a good strong wind and dispersed it completely.

The Washington Monument stopped glowing. The rift closed, and the little spellbook disappeared from my hand.

I moved towards Set, who was still ensnared in ropes of white energy. I'd spoken his true name. He wasn't going anywhere just yet.

"You both saw the serpent in the clouds," I said. "Apophis."

Carter nodded, stunned. "He was trying to break into the mortal world, using the Red Pyramid as a gateway. If its power had been unleashed..." He looked down in revulsion at the pile of sand that had once been a demon. "Set's lieutenant-Face of Horror-he was possessed by Apophis all along, using Set to get what he wanted."

"Ridiculous!" Set glared at me and struggled against his bonds. "The snake in the clouds was one of your tricks, Isis. An illusion."

"You know it wasn't," I said. "I could've sent you into the abyss, Set, but you saw the real enemy. Apophis was trying to break out of his prison in the Duat. His voice possessed Face of Horror. He was using you."

"No one uses me!"

Carter let his warrior form disperse. He floated to the ground and summoned his sword back to his hand. "Apophis wanted your explosion to feed his power, Set. As soon as he came through the Duat and found us dead, I'm betting you would've been his first meal. Chaos would've won."

"I am chaos!" Set insisted.

"Partially," I said. "But you're still one of the G.o.ds. True, you're evil, faithless, ruthless, vile-"

"You make me blush, sister."

"But you're also the strongest G.o.d. In the ancient times, you were Ra's faithful lieutenant, defending his boat against Apophis. Ra couldn't have defeated the Serpent without you."

"I am pretty great," Set admitted. "But Ra is gone forever, thanks to you."

"Maybe not forever," I said. "We'll have to find him. Apophis is rising, which means we'll need all the G.o.ds to battle him. Even you."

Set tested his bonds of white energy. When he found he couldn't break them, he gave me a crooked smile. "You suggest an alliance? You'd trust me?"

Carter laughed. "You've got to be kidding. But we've got your number, now. Your secret name. Right, Sadie?"

I closed my fingers, and the bonds tightened around Set. He cried out in pain. It took a great deal of energy, and I knew I couldn't hold him like this for long, but there was no point telling that to Set.

"The House of Life tried banishing the G.o.ds," I said. "It didn't work. If we lock you away, we're no better than they are. It doesn't solve anything."

"I couldn't agree more," Set groaned. "So if you'll just loosen these bonds-"

"You're still a villainous piece of sc.u.m," I said. "But you have a role to play, and you'll need controlling. I'll agree to release you-if you swear to behave, to return to the Duat, and not cause trouble until we call you. And then you'll make trouble only for us, fighting against Apophis."

"Or I could chop off your head," Carter suggested. "That would probably exile you for a good long while."

Set glanced back and forth between us. "Make trouble for you, eh? That is my specialty."

"Swear by your own name and the throne of Ra," I said. "You will leave now and not reappear until you are called."

"Oh, I swear," he said, much too quickly. "By my name and Ra's throne and our mother's starry elbows."

"If you betray us," I warned, "I have your name. I won't show you mercy a second time."

"You always were my favorite sister."

I gave him one last shock, just to remind him of my power, and then let the bindings dissolve.

Set stood up and flexed his arms. He appeared as a warrior with red armor and red skin, a black, forked beard, and twinkling, cruel eyes; but in the Duat, I saw his other side, a raging inferno just barely contained, waiting to be unleashed and burn everything in its path. He winked at Horus, then pretended to shoot me with a finger gun. "Oh, this will be good. We're going to have so much fun."

"Begone, Evil Day," I said.

He turned into a pillar of salt and dissolved.

The snow in the National Mall had melted in a perfect square, the exact size of Set's pyramid. Around the edges, a dozen magicians still lay pa.s.sed out. The poor dears had started to stir when our portal closed, but the explosion of the pyramid had knocked them all out again. Other mortals in the area had also been affected. An early-morning jogger was slumped on the sidewalk. On nearby streets, cars idled while the drivers took naps over the steering wheels.

Not everyone was asleep, though. Police sirens wailed in the distance, and seeing as how we'd teleported practically into the president's backyard, I knew it wouldn't be long before we had a great deal of heavily armed company.

Carter and I ran to the center of the melted square, where Amos and Zia lay crumpled in the gra.s.s. There was no sign of Set's throne or the golden coffin, but I tried to push those thoughts out of my mind.

Amos groaned. "What..." His eyes clouded over with terror. "Set...he...he..."

"Rest." I put my hand on his forehead. He was burning with fever. The pain in his mind was so sharp, it cut me like a razor. I remembered a spell Isis had taught me in New Mexico.

"Quiet," I whispered. "Hah-ri."

Faint hieroglyphs glowed over his face: Amos drifted back to sleep, but I knew it was only a temporary fix.

Zia was even worse off. Carter cradled her head and spoke rea.s.suringly about how she would be fine, but she looked bad. Her skin was a strange reddish color, dry and brittle, as if she'd suffered a horrible sunburn. In the gra.s.s around her, hieroglyphs were fading-the remains of a protective circle-and I thought I understood what had happened. She'd used her last bit of energy to shield herself and Amos when the pyramid imploded.

"Set?" she asked weakly. "Is he gone?"

"Yes." Carter glanced at me, and I knew we'd be keeping the details to ourselves. "Everything's fine, thanks to you. The secret name worked."

She nodded, satisfied, and her eyes began to close.

"Hey." Carter's voice quavered. "Stay awake. You're not going to leave me alone with Sadie, are you? She's bad company."

Zia tried to smile, but the effort made her wince. "I was...never here, Carter. Just a message-a placeholder."

"Come on. No. That's no way to talk."