Timidly, I reach forward, almost certain he will whirl the pistol around and shoot me at the last moment. But he does not. My fingers wrap around the butt and my forefinger touches the trigger. The pistol is cold and heavy in my hand. But I am not trembling as I aim it at him.

"Don't shoot me," he says, and I wonder why, then, he has given me the choice.

"Come with me to the Italian embassy," he says. "I will turn myself in to Interpol and confess everything I know about my family.

"My uncle made me believe that the isotope was our way out. But I can see now that he was lying. I could see the greed in his eyes through the video phone. He is never going to stop. Ever. Not for one legitimate drug. Not for a thousand. Not ever.

"I am the family's computer hacker. I've never actually killed anyone. I mean, I've never pulled the trigger. I know that isn't much of an excuse. But maybe if I tell them everything, they will go easy on me. Maybe one day I can even be the pagan theologist I would have been had I not been born into the Rossi crime family.

"But, please, don't shoot me. All that will do is ruin you. And I don't want to be responsible for destroying yet another life. Especially yours."

It is hard to believe that the broken man before me now is the charming student who led me through the ruins of Pompeii. It is hard to believe that the compassionate young man who led me from the Naples police station is the same one who set me up to be brought there, who twice tracked me through the GPS on my phone, and who turned my private data over to the oldest crime family in Naples. And it is hard to believe that this remorseful boy has been involved in so many murders.

How many have there been in his lifetime? I wonder.

I pull back the hammer of the gun.

Now my hand is trembling, with rage.

I cannot see Dante Giordano. I can only see Lawrence Naden. I can only see the man whose gang warfare killed my son, Christopher, sixteen years ago.

I can shoot him between the eyes. Right now. My aim is true. I know it is true because I have rigorously trained myself. I have envisioned this moment for sixteen years.

And when I am finished, after I have finally snuffed out the source of my hatred, I can walk away from this Cairo park, and nobody will ever know, or care, what happened to this drug runner from Naples.

I move toward him. I am practically shoving the gun into his face, and he does not move. I begin to weep sixteen years worth of furious tears. They pour from my blackened heart.

And then I lower the gun and collapse onto the grass in front of Dante.

"You... are right," I sob. "Killing you... won't bring back Jeff. It won't bring back John. It won't bring back... Christopher, either. It will only make me a killer. And I don't want to be a killer again."

Dante looks at me intently, and I realize that we understand each other.

She took one earring off, and dropped the pearl in the vinegar, and when it was wasted away, swallowed it.

-Natural History Pliny the Elder (2379 CE)

Chapter Twenty-Eight.

What he wants is in this lab...

Is it because women do not make war, as men do?

... We make our own medicines, Katrina...

When the sky opened and the gods cast their anger upon our enemies, the wine soured and the nardos by the bedsides turned from green to red.

It is too late. At last, I understand how to generate the isotope, but it is too late. John is dead, and only Rossi remains in my laboratory in Naples.

With Dante, I return to the bench I had been sitting on. My phone is still upon it, and the video call is still connected. I cannot look at the screen.

The image is in my mind nonetheless. I envision John lying on the floor of a laboratory in Naples. His head is blown open.

But Dante picks up my phone. He gasps. "What-? Who are you?"

He turns the phone around to show me the image on its screen, and I have no choice but to see it.

"Oh, my God," I whisper fiercely as the creased, bearded face of Aldo de Luca smiles up at me. It is the first time I have seen him smile.

De Luca steps away from the camera, and behind him John is waking up again.

"What happened to Rossi?" I ask.

"Oh," de Luca says casually. "This piece of shit?" He retrieves John's smartphone from the lab bench and turns the video screen toward the floor. The camera's field of vision falls upon the body of Rossi. He is lying almost peacefully, having fallen onto one arm. There is a single gunshot wound through his back. Aldo de Luca kicks him.

"I... I don't understand..." I trail off.

"Thank you," I say then, and tears are streaming down my face once again.

Aldo de Luca smiles. "You don't promise someone a hundred thousand euros and then expect them to just disappear, do you? You showed me this place. You told me you were in trouble. And..."

His smile widens.

"What?" I ask.

"Do you remember that day when we came to these labs?" he asks. "Do you remember taking me through the tunnels, walking past the corpses in the underground chamber?"

I cast my mind back, but I cannot comprehend where he is leading.

"I looked at that pregnant woman, and I looked at you. And I knew then what you know now."

He knew I was pregnant before I did. And he was looking out for me all this time.

"Thank you" is all I can say, again, through my tears.

"I did what anyone would have done for a pregnant lady who has just lost her husband," he says. "And besides, Naples is my city."

I can only stare at the screen of my phone, confused.

"Don't misunderstand me," de Luca says. "I am where I am in life because of my own mistakes. But Naples is not easy on people like me. It is not easy for someone like me to improve his own situation. And that is because of people like this piece of shit." For emphasis, he kicks the body of Rossi one more time. "I guess you can say I have had enough."

When John is awake, I tell him I now know how to generate the isotope.

"I don't get it," he says. "We tried everything. We put the two plants together. We mashed parts of them up. We put parts of them in water. We even set parts of them on fire. Nothing happened."

"Try acetic acid," I say.

"The legend of Cleopatra and the pearl is true," I say. "It was true in her day, it was true when it was documented by Pliny the Elder, and it is true today. Cleopatra dissolved a pearl in vinegar and drank it.

"She obviously kept vinegar around for personal use. Possibly for experimentation. It is, after all, an acid. And it exists in hospitals and laboratories everywhere.

"I don't know if the phenomenon she observed in the nardo was accidental or deliberate. Maybe there was an earthquake-maybe that was the sky opening-and a bottle of acetic acid tipped over onto a bouquet of lotus and papyrus like the bouquets I have seen decorating almost every temple in Egypt. Maybe someone walked by and bumped something. Or maybe she was really experimenting.

"All I know is that, in the nardo document, she describes how to generate the isotope. Soured wine is vinegar. She speaks of it. She speaks of the nardo-the lotus-and she uses the medium of papyrus.

"Try acetic acid," I repeat. "Try dropping a small sample of each plant into acetic acid, just as Cleopatra did with the pearl."

John does as instructed, and nothing happens.

"God damn it!"

I throw the iPhone as far from myself as possible and begin pacing through the park. I am vaguely aware that I am waving a semi-automatic pistol randomly.

What are we missing?

Nothing.

The obvious answer is upon me, and I bury my face in my hands, the hard metal of the pistol smashing into my cheek.

The isotope was never real. It was a myth all along. And I, a scientist all my life, have just been desperate enough to believe in magic.

"Katrina?"

I hear a voice behind me, and I turn.

"Try using the document." It is Dante.

"Huh?" For a moment, I just stare at him in disbelief, but then my heart jumps. I clasp a hand over my mouth. What if?

I run to retrieve my discarded phone from the dirt beneath a tree. A large, jagged crack now runs down its screen, but the video is still running. John sits with one hand on his forehead, staring absently at the floor.

"John!" I say, and he looks up. "There's one more thing we can try. Try ripping a corner from the nardo document itself. Because that document is composed of Cleopatra's papyrus, the papyrus from two thousand years ago. Just like the lotus I pulled from the base of the Aswan Temple of Isis is Cleopatra's nardo. Spikenard. S N. Lotus, in ancient Egyptian."

One more time, John follows my suggestion, and I watch intently. Aldo de Luca watches intently. Dante, now standing beside me, is watching intently. And a flush of red passes momentarily through the nardo.

The battery on my phone is dying as I leave John with last minute instructions. He is to gather patients into the largest groups he can because the ancient papyrus in the nardo document is finite. And the effect of the isotope lasts only minutes.

The patients must be there when it occurs.

John leaves Naples with a logistical nightmare on his hands as he reaches out to the long list of people who need to come into contact with the transient superheavy isotope we have just named Vesuvium.

He is either heedless or mad-for, indeed, I have heard and believed that he has been bewitched by that accursed woman.

Octavian, on Antony and Cleopatra -Roman History Cassius Dio (ca. 150235 CE)

Chapter Twenty-Nine.

Six months have passed, but the city of Cairo is instantly familiar. I smile at the honking of horns and the faint sweet scent of smog as I step out of the airport into a whirlpool of taxi drivers.

I remember the cumbersome suitcases I was dragging when I was here six months ago. This time, a small overnight bag is slung over my shoulder. It is now January, and the weather is warm but not uncomfortably hot-a welcome change from the cauldron I endured here in July.

My hair is auburn again, and longer. Soon it will once again be down to my waist. I no longer mind the attention directed at me in the Cairo streets.

I negotiate a cab ride into the city and then catch a Metro from Midan Tahrir. The women in the car kindly move aside to offer me the seat closest to the doors. I smile and thank them in English, waving a weary hand before I sit down heavily. I know they understand my gratitude if not my words.

Twenty minutes later, the Metro screeches to a halt. I use the metal hand rail to heave myself to a standing position. I step out and begin walking. My limp is almost gone now, but the characteristic waddle of a woman in the end stages of pregnancy is creeping into my gait. I walk more slowly now than I used to. Yet, I am eager as I approach the destination I have traveled from San Diego to Cairo to understand. As the birth of my son approaches, it is time to face the consequences of my actions. And, hopefully, time to close this chapter of my life.

I pay my entrance fee and purchase a small street map. Then I step into the walled, ancient city of Coptic Cairo.

I am early. Slowly, I stroll through the dusty, crooked streets of the birthplace of Egyptian Christianity. Churches and convents line both sides of the streets. I wander into a church and am greeted by an ornate interior of gold and ivory. An old man is at its altar, lighting candles. I leave him alone and return to the street.

I reach into my bag and withdraw the map I purchased at the entrance to the city. I turn and continue down another street. At its end, the ancient city opens into a large pair of cemeteries, separated by a narrow walkway. One cemetery, historically, is Greek Catholic. The other is Greek Orthodox. But within them, I see a diversity I would never have imagined.

Each cemetery contains hundreds, maybe thousands of final resting places ranging from simple headstones to elaborate mausoleums. They are inscribed in Aramaic, Arabic, Hebrew, Greek, Latin, and, occasionally, even English. Some of the monuments are centuries old, and others quite recently erected. Some of them are graced with flowers. Some with photographs.

I brush the fallen leaves off of a stone bench, shaded beneath a tall tree, and sit down to wait.

It is our second date. We step out of the Louvre, and Jeff takes my hand for the first time. I am terrified.

"Are you going to contact the chemistry teacher?" I ask. "The one who told you the bogus story of the caduceus?"

"Hell yeah!" he says. "I can't wait to call Dr. Bond and gloat!"

I giggle and elbow him in the ribcage. "Why am I not surprised?"

"Because we are two of a kind," he banters back and throws his arm around me as if it is the most natural of things.

We wander without speaking into the quiet solitude of the Tuileries Gardens behind the Louvre. The rain has now abated to a soft drizzle, and we walk through the garden slowly, hand in hand. At first, neither of us speaks. My eyes, always avoiding his, shift between the ground before my feet and the soft grassy area surrounding us. I feel drunk with the words echoing through my head.

We are two of a kind.

Never before have I met a man whose intellect aroused me as much as the chemistry between us. Forever skeptical of the old cliche that I would know when I met the right man, I now feel with conviction that I know. And it has only been two days. I struggle to retain my comfort zone of logic, but my heart is pounding.

We reach a large circular fountain in the center of the garden, and Jeff voices my inner thoughts exactly. "You seem too good to be true," he says. I stop walking and am grasping for a safe response when he pulls me toward him and kisses me for the first time. And every remaining shred of my instinctive resistance dissolves.

I hear quiet footsteps, and I awaken from my daydream. She is approaching.