To Becky,

Every journey leads me home to you

WHEN TRAVELING THROUGH WASHINGTON, DC, one expects to see a few snakes in human clothing. Still, I was concerned when a two-headed boa constrictor boarded our train at Union Station.

The creature had threaded himself through a blue silk business suit, looping his body into the sleeves and trouser legs to approximate human limbs. Two heads protruded from the collar of his dress shirt like twin periscopes. He moved with remarkable grace for what was basically an oversize balloon animal, taking a seat at the opposite end of the coach, facing our direction.

The other passengers ignored him. No doubt the Mist warped their perceptions, making them see just another commuter. The snake made no threatening moves. He didn’t even glance at us. For all I knew, he was simply a working-stiff monster on his way home.

And yet I could not assume…

I whispered to Meg, “I don’t want to alarm you—”

“Shh,” she said.

Meg took the quiet-car rules seriously. Since we’d boarded, most of the noise in the coach had consisted of Meg shushing me every time I spoke, sneezed, or cleared my throat.

“But there’s a monster,” I persisted.

She looked up from her complimentary Amtrak magazine, raising an eyebrow above her rhinestone-studded cat-eye glasses. Where?

I chin-pointed toward the creature. As our train pulled away from the station, his left head stared absently out the window. His right head flicked its forked tongue into a bottle of water held in the loop that passed for his hand.

“It’s an amphisbaena,” I whispered, then added helpfully, “a snake with a head at each end.”

Meg frowned, then shrugged, which I took to mean Looks peaceful enough. Then she went back to reading.

I suppressed the urge to argue. Mostly because I didn’t want to be shushed again.

I couldn’t blame Meg for wanting a quiet ride. In the past week, we had battled our way through a pack of wild centaurs in Kansas, faced an angry famine spirit at the World’s Largest Fork in Springfield, Missouri (I did not get a selfie), and outrun a pair of blue Kentucky drakons that chased us several times around Churchill Downs. After all that, a two-headed snake in a suit was perhaps not cause for alarm. Certainly, he wasn’t bothering us at the moment.

I tried to relax.

Meg buried her face in her magazine, enraptured by an article on urban gardening. My young companion had grown taller in the months that I’d known her, but she was still compact enough to prop her red high-tops comfortably on the seatback in front of her. Comfortable for her, I mean, not for me or the other passengers. Meg hadn’t changed her shoes since our run around the racetrack, and they looked and smelled like the back end of a horse.

At least she had traded her tattered green dress for Dollar General jeans and a green VNICORNES IMPERANT! T-shirt she’d bought at the Camp Jupiter gift shop. With her pageboy haircut beginning to grow out and an angry red zit erupting on her chin, she no longer looked like a kindergartener. She looked almost her age: a sixth grader entering the circle of hell known as puberty.

I had not shared this observation with Meg. For one thing, I had my own acne to worry about. For another thing, as my master, Meg could literally order me to jump out the window and I would be forced to obey.

The train rolled through the suburbs of Washington. The late-afternoon sun flickered between the buildings like the lamp of an old movie projector. It was a wonderful time of day, when a sun god should be wrapping up his work, heading to the old stables to park his chariot, then kicking back at his palace with a goblet of nectar, a few dozen adoring nymphs, and a new season of The Real Goddesses of Olympus to binge-watch.

Not for me, though. I got a creaking seat on an Amtrak train and hours to binge-watch Meg’s stinky shoes.

At the opposite end of the car, the amphisbaena still made no threatening moves…unless one considered drinking water from a nonreusable bottle an act of aggression.

Why, then, were my neck hairs tingling?

I couldn’t regulate my breathing. I felt trapped in my window seat.

Perhaps I was just nervous about what awaited us in New York. After six months in this miserable mortal body, I was approaching my endgame.

Meg and I had blundered our way across the United States and back again. We’d freed ancient Oracles, defeated legions of monsters, and suffered the untold horrors of the American public transportation system. Finally, after many tragedies, we had triumphed over two of the Triumvirate’s evil emperors, Commodus and Caligula, at Camp Jupiter.

But the worst was yet to come.

We were heading back to where our troubles began—Manhattan, the base of Nero Claudius Caesar, Meg’s abusive stepfather and my least favorite fiddle player. Even if we somehow managed to defeat him, a still more powerful threat lurked in the background: my archnemesis, Python, who had taken up residence at my sacred Oracle of Delphi as if it were some cut-rate Airbnb.

In the next few days, either I would defeat these enemies and become the god Apollo again (assuming my father Zeus allowed it) or I would die trying. One way or the other, my time as Lester Papadopoulos was coming to an end.

Perhaps it wasn’t a mystery why I felt so agitated.…

I tried to focus on the beautiful sunset. I tried not to obsess about my impossible to-do list or the two-headed snake in row sixteen.

I made it all the way to Philadelphia without having a nervous breakdown. But as we pulled out of Thirtieth Street Station, two things became clear to me: 1) the amphisbaena wasn’t leaving the train, which meant he probably wasn’t a daily commuter, and 2) my danger radar was pinging more strongly than ever.

I felt stalked. I had the same ants-in-the-pores feeling I used to get when playing hide-and-seek with Artemis and her Hunters in the woods, just before they jumped from the brush and riddled me with arrows. That was back when my sister and I were younger deities and could still enjoy such simple amusements.

I risked a look at the amphisbaena and nearly jumped out of my jeans. The creature was staring at me now, his four yellow eyes unblinking and…were they beginning to glow? Oh, no, no, no. Glowing eyes are never good.

“I need to get out,” I told Meg.

“Shh.”

“But that creature. I want to check on it. His eyes are glowing!”

Meg squinted at Mr. Snake. “No, they’re not. They’re gleaming. Besides, he’s just sitting there.”

“He’s sitting there suspiciously!”

The passenger behind us whispered, “Shh!”

Meg raised her eyebrows at me. Told you so.

I pointed at the aisle and pouted at Meg.

She rolled her eyes, untangled herself from the hammock-like position she’d taken up, and let me out. “Don’t start a fight,” she ordered.

Great. Now I would have to wait for the monster to attack before I could defend myself.

I stood in the aisle, waiting for the blood to return to my numb legs. Whoever invented the human circulatory system had done a lousy job.

The amphisbaena hadn’t moved. His eyes were still fixed on me. He appeared to be in some sort of trance. Maybe he was building up his energy for a massive attack. Did amphisbaenae do that?

I scoured my memory for facts about the creature but came up with very little. The Roman writer Pliny claimed that wearing a live baby amphisbaena around your neck could assure you a safe pregnancy. (Not helpful.) Wearing its skin could make you attractive to potential partners. (Hmm. No, also not helpful.) Its heads could spit poison. Aha! That must be it. The monster was powering up for a dual-mouthed poison vomit hose-down of the train car!