Back at the steel door, I suited up. I readied two syringes: one with vitriol, one with water. “Meg, stand back.”

“I…Okay.” She pinched her nose against the stench as I squirted oil of vitriol around the door. Vaporous tendrils curled from the seams. “What is that stuff?”

“Back in medieval times,” I said, “we used oil of vitriol for its healing properties. No doubt that’s why Commodus had some in his infirmary. Today we call it sulfuric acid.”

Meg flinched. “Isn’t that dangerous?”

“Very.”

“And you healed with it?”

“It was the Middle Ages. We were crazy back then.”

I held up the second syringe, the one filled with water. “Meg, what I’m about to do—never, ever try this on your own.” I felt a bit silly giving this advice to a girl who regularly fought monsters with golden swords, but I had promised Bill Nye the Science Guy I would always promote safe laboratory practices.

“What’s going to happen?” she asked.

I stepped back and squirted water into the door seams. Immediately the acid began to hiss and spit more aggressively than the Carthaginian Serpent. To speed the process along, I sang a song of heat and corrosion. I chose Frank Ocean, since his soulful power could burn its way through even the hardest substances.

The door groaned and creaked. At last it fell inward, leaving a steaming wreath of mist around the frame.

“Whoa,” Meg said, which was probably the highest compliment she’d ever given me.

I pointed to the cardboard supply box near her feet. “Hand me that baking soda, would you?”

I sprinkled powder liberally around the doorway to neutralize the acid. I couldn’t help smirking at my own ingenuity. I hoped Athena was watching, because WISDOM, BABY! And I did it with so much more style than Old Gray Eyes.

I bowed to Meg with a flourish. “After you, Chia Girl.”

“You actually did something good,” she noted.

“You just had to step on my moment.”

Inside, we found a twenty-foot-square storage area holding just one item. The Throne of Mnemosyne hardly deserved the name throne. It was a straight-backed chair of sanded white birch, devoid of decoration except for the carved silhouette of a mountain on the seat back. Ugh, Mnemosyne! Give me a proper golden throne encrusted with ever-flaming rubies! Alas, not every deity knows how to flaunt it.

Still, the chair’s simplicity made me nervous. I’ve found that many terrible and powerful items are quite underwhelming in appearance. Zeus’s lightning bolts? They don’t look menacing until my father throws them. The trident of Poseidon? Please. He never scrubs the seaweed and moss off that thing. And the wedding dress Helen of Troy wore to marry Menelaus? Oh, gods, it was so drab. I told her, “Girl, you have got to be kidding me. That neckline doesn’t work for you at all!” Then Helen put it on, and wow.

“What’s the mountain design?” Meg stirred me from my reverie. “Olympus?”

“Actually, no. I’m guessing that would be Mount Pierus, where the goddess Mnemosyne gave birth to the Nine Muses.”

Meg scrunched up her face. “All nine of them at once? Sounds painful.”

I’d never thought about that. Since Mnemosyne was the goddess of memory, with every detail of her eternal existence engraved on her brain, it did seem strange that she’d want a reminder of her labor and delivery experience carved on her throne.

“Whatever the case,” I said, “we’ve tarried too long. Let’s get the chair out of here.”

I used my roll of medical tape to make shoulder straps, turning the chair into a makeshift backpack. Who said Leo was the only handy person on our team?

“Meg,” I said, “while I’m doing this, fill those syringes with ammonia.”

“Why?”

“Just for emergencies. Humor me.”

Medical tape is wonderful stuff. Soon Meg and I both had bandoliers of ammonia syringes, and I had a chair on my back. The throne was a light piece of furniture, which was fortunate, since it was knocking around with my ukulele, my bow, and my quiver. I added a few scalpels to my bandolier, just for fun. Now all I needed was a bass drum and some juggling pins and I could be a one-man traveling show.

I hesitated in the corridor. In one direction, the hallway extended about a hundred feet before angling left. The alarms had stopped blaring, but from around that corner came an echoing roar like ocean surf or a cheering crowd. Multicolored lights flashed across the walls. Just looking in that direction made me nervous.

Our only other option would take us back to the Meg McCaffrey Memorial Wall of Chia.

“Fastest exit,” I said. “We may have to retrace our steps.”

Meg stood enthralled, her ear tilted toward the distant roar. “There’s…something down there. We need to check it out.”

“Please, no,” I begged. “We’ve rescued the prisoners. We found Festus. We scored a lovely piece of furniture. That’s a full day’s work for any hero!”

Meg straightened. “Something important,” she insisted.

She summoned her swords and strode toward the strange lights in the distance.

“I hate you,” I muttered.

Then I shouldered my magical chair and jogged after her—around the corner and straight into a vast spotlighted arena.

Big birds are evil

They charge me with razor legs

I die and it hurts

I WAS NO STRANGER to stadium concerts.

In ancient times, I played a dozen sold-out shows at the amphitheater in Ephesus. Frenzied young women threw their strophiae at me. Young men swooned and fainted. In 1965, I sang with the Beatles at Shea Stadium, though Paul would not agree to turn up my microphone. On the recordings, you can’t even hear my voice on “Everybody’s Tryin’ to Be My Baby.”

However, none of my previous experiences prepared me for the emperor’s arena.

Spotlights blinded me as we emerged from the corridor. The crowd cheered.

As my eyes adjusted, I saw that we stood at the fifty-yard line of a professional football stadium. The field was arranged in an odd fashion. Around the circumference ran a three-lane racetrack. Pincushioning the artificial turf, a dozen iron posts anchored the chains of various beasts. At one post, six combat ostriches paced like dangerous merry-go-round animals. At another, three male lions snarled and blinked at the spotlights. At a third, a sad-looking elephant swayed, no doubt unhappy that she’d been outfitted in spiked chain mail and an oversize Colts football helmet.

Reluctantly, I raised my eyes to the stands. In the sea of blue seats, the only occupied section was the end zone on the left, but the crowd was certainly enthusiastic. Germani banged their spears against their shields. The demigods of Commodus’s Imperial Household jeered and yelled insults (which I will not repeat) about my divine person. Cynocephali—the tribe of wolf-headed men—howled and tore at their Indianapolis Colts souvenir jerseys. Rows of blemmyae clapped politely, looking perplexed at the rude behavior of their peers. And of course, an entire section of the stands was filled with wild centaurs. Honestly, you can’t have a sporting event or bloodbath anywhere without them somehow getting wind of it. They blew their vuvuzelas, sounded air horns, and trampled all over one another, sloshing root beer from their double-cup drinking hats.