The entrance to the secret cave was buried deep below the earth’s surface. I knew because I was part of the small group that had discovered it. When we had broken the rock apart, it had revealed a long vertical shaft that had blown bitter cold wind out at us. That should’ve been our first warning. Now one miner lay dead somewhere at the bottom, and they’d had to carry Fidelius out of here, still chewing on his fist. Not that Radulf cared. In fact, considering that he knew what I’d overheard, he probably hoped I’d join their fates.

“Remove this boy’s chains,” Radulf ordered Sal. “He cannot do what is required of him while wearing chains.”

But Sal shook his head. “You see how far he ran while wearing chains. Imagine if he didn’t have them.”

“It’s never been chains that kept me here,” I said. It was Livia’s reluctance to leave. The idea of escaping frightened her just as much as it beckoned me. But she was younger, and didn’t remember freedom like I did.

“Unchain him,” Radulf said.

Sal reached for his keys and did as he was told. He was then ordered to tie a long rope around my waist. It would be his job to lower me to the bottom of the cave. If there was a bottom.

Looking down into the cave’s black entrance, I was sure Fidelius had been right. This was forbidden earth. My chances of returning weren’t good, and where would that leave Livia? Without me, there was no one to take care of her. Except for Sal, which was worse than having nobody at all.

After Sal tied the rope, Radulf dismissed him so that we could talk in private. He checked the knot, but offered no sympathy for the likelihood that I would die, nor did I expect any. He only said, “If it truly is Caesar’s lost treasure down there, then you will look for only one thing, a bulla made entirely of gold. Do you know what a bulla is?”

I rolled my eyes. Every freeborn boy in Rome wore the pendant around his neck. Not having one identified me as worthless to the empire. So yes, of course I knew what it was.

“Good. The one I want will have a griffin carved on one side and Caesar’s initials on the other. Do you know your letters?”

“All the important ones.” He smiled at my comment, though I hoped he wouldn’t make too much of it. My mother had taught me to recognize Latin letters, but got no further before she was sold away. I had no idea what to do with them beyond that.

“That bulla is all I want,” Radulf said. “The rest belongs to the empire.”

I squinted back at him, recalling the conversation I had just overheard. If Radulf wanted a way to crush the Roman Empire, a bulla would do him no good. Bullas were given to wealthy young boys as charms against bad luck. Personally, I doubted they worked. Since they had been born wealthy, I figured those boys already had all the luck they needed in life. Regardless, once a boy became a man, he put away the bulla along with his other childish things. Caesar would have done the same.

Radulf grabbed my arm and leaned in closer. “I know what you overheard from me, and you would be wise to forget it. If you defy me, it will not go well for you.”

I believed him. He’d been in my life for less than an hour and my hopes had already taken a significant turn for the worse. “All I care about is getting back to the surface,” I said. “The rest is your concern, not mine.”

His expression warmed to that. With his grip on me tighter than ever, he said, “Once you find the bulla, do not put it on; do not hold it too close. Just carry it back to me. If you do as I ask, then I will take you away from this place, even bring you back to Rome with me. Your sister too.”

My mouth dropped open in surprise. I didn’t like Radulf, but I’d rather not like him in Rome than stay here in the mines for another minute. That made it harder to ask the question still hanging in the air. “What if I don’t find the bulla?”

“Then Sal won’t bring you back up.”

My hands began shaking, and I pressed them against my leg to calm the nerves. “I might not come back anyway. Others have tried.”

Radulf looked me over again, and the barest hint of a smile escaped his stern expression. I wasn’t sure if that was a sign of hope, or one of cruelty.

With that, Radulf called Sal back in to join us. Then he hoisted me up to the cavity in the rock, handed me a torch, and ordered Sal to lower me inside.

The darkness was blacker than anything I’d ever seen. Blacker than night, or even the deepest mine tunnels. Light was an enemy to this place. The torch I carried helped a little, but it was so bright, I could see nothing else. An icy breeze assaulted me next. As miners, we had all become used to cold, but this air seemed to flow right through me, and I half expected the torch to freeze in place.

I held my breath at first. Mostly from fear, but also because of the possibility that the air was poisonous. We’d seen it before in the mines. Air that is trapped underground for centuries sometimes kills the first few miners to breathe it in. It had never been a question in my mind that I would die young. Killed during an escape attempt or during an uprising, maybe — those were honorable deaths, at least. But I refused to have stories told about me dying from bad air.

As Sal lowered me down, I tried to think of what I knew about Julius Caesar. My mother had once told me a story about when Caesar was kidnapped by pirates on the Aegean Sea. Offended that they asked only twenty talents of silver for his ransom, Caesar demanded they increase it to fifty. Once it was paid and he went free, he returned to the island where he’d been held and executed the pirates himself. Then he recovered his fifty talents, and all their possessions too. It was no surprise that he went on to become a military general who won every war he ever fought.

If Caesar was that powerful, then who was I to dare enter his sealed cave?

The rope above me was sliding against a very sharp rock. Using the torch to look up, I saw strands of it beginning to fray. And when I swung the torch down, I was still too high to see the cave floor. I wondered if I had any chance of landing before Sal ran out of rope. If he did, would he pull me back up, or cut it? Without Radulf standing right beside him up there, he probably would’ve cut it already.

Finally, I had no choice but to take a breath, and was relieved to discover that the air was stale, but not poisonous. My relief was short-lived, however. The same breeze I drew into my body also snuffed out my torch, leaving me in complete darkness.

I called up to Sal that the light was gone, but he either didn’t hear me or didn’t care. Since he was using this cave to get rid of me, it was safe to assume the latter. And I continued to drop lower and lower. Into nothingness. Into the underworld.

After several long minutes, my feet collided with something hard. The ground, I hoped, but I didn’t trust it yet. So with my hands, I groped around blindly. I found rock beneath me, but different from the type of rock we mined higher up. It was less porous, and sharper. It also seemed fairly flat, but before I had the chance to test a step, Sal lowered me down onto it. Whatever this was, I was committed now.

I was on my knees, and put my hands down again to determine how much room I had, but I touched upon something different than before. It wasn’t dirt, but it wasn’t as hard as rock either. It felt more like wood, a rounded, carved piece as smooth as — my breath caught in my throat. It was as smooth as bone. And round … like a skull. I ran my hands along the ground and felt more skulls and other bones.

I choked on my own breath, suddenly ill. Who were these people? Were they sacrifices made at Diana’s temple? Or invaders whose discovery had become their tomb? A worse thought still: Was I meant to join them?