“So, what are we doing here again?” I asked as we walked through the airport.

“I thought I already explained this,” Dad said with a sigh. “Oh well, here we go again.”

He adjusted his backpack before continuing.

“After the war, two countries were completely annihilated, and the survivors immigrated to neighboring nations. It was a tragedy that shook the entire world. After that, the remaining countries decided they had to do something different. They agreed to work toward lasting world peace.”

“How?” I asked.

“As a symbol of that peace—and as a way to make it last—each continent agreed to choose its smartest student and send them to a special school. There, you’ll learn together from one another and from some of the world’s greatest teachers.”

“That’s what all the tests at school have been about,” I interrupted.

Dad nodded. “Exactly. And you were chosen.”

I stopped walking for a second.

“Wait… me?”

“You,” Dad said with a smile. “Which means we’re flying to Paris. Your education will continue at a school hidden beneath the Champ de Mars. The entrance is concealed inside one of the Eiffel Tower’s four legs, and only students, teachers, and a handful of world leaders even know it exists.”

I stared at him.

“And… I won’t see you again until Christmas.”

“What about Thanksgiving?” I asked.

Dad gave a small shrug. “Since Thanksgiving is only celebrated in America, it isn’t recognized as a school holiday. You’ll have to wait until Christmas break to come home.”

We touched down in Paris in the wee hours of the night, with just enough time for me to grab a croissant and Dad to drink a black coffee. I hadn't slept at all on the flight over the Atlantic Ocean. You would think that the most powerful world leaders would be able to book me a private jet, or at least a plane with more comfortable seats, but no. So, as we approached the Eiffel Tower, my feet dragged and my eyelids drooped.

I looked down at the acceptance letter, blinking a few times until the words came into focus. "You must arrive at the School at exactly two hours prior to sunrise. For in-processing, start at the northwest corner of the Eiffel Tower and proceed counterclockwise. Before you begin in-processing, you must say your goodbyes to your parents, guardians, or anyone else accompanying you to the Tower. GOOD LUCK IS NO MATCH FOR SKILL."

This was it. I hugged my dad goodbye, too tired to really feel sad in the moment--though I knew it would hit me later, once I had gotten a good night's sleep. Then I took a deep breath and walked toward the corner of the tower: the northwest leg.

I wasn't sure what I expected to find. It definitely wasn't a collection of random stickers stuck to the wall like a paper collage. No, they weren't random--some of the stickers were single letters, arranged in rows and groups. The letters looked like they had been placed there haphazardly by tourists at first glance, but there was no mistaking their perfect alignment: these were purposeful.

In-processing, I thought. To prove that we're really smart enough to be here.

I cracked the code in three minutes. It really wasn't that hard: they had already given me the key to decode it in the acceptance letter. Using the phrase "GOOD LUCK IS NO MATCH FOR SKILL," I reordered the letters of the alphabet so that each one substituted for a different one. When I was finished, I noted down the hidden message on my phone.

"Next lock is factorial of seven."

Heart in my throat, I made my way around the tower to the southwest side. I had never been good at factorial numbers, but I understood the concept: a number multiplied by every number before it. For seven, that would be... one times two times three times four times five times six times seven. I found a tiny combination lock between two struts of metal and stared at it, putting the right number together in my mind.

5,040. It took a while, but I turned the wheels to those four numbers and suddenly heard a clanking sound from the southeast side: metal shifting and moving, revealing another lock.

This time, I ran to the next leg of the tower. I smiled when I saw the puzzle: a square of nine tiles, each containing a number from one to nine. The magic square. A classic. I rearranged the tiles so that each row and column added up to 15 and was rewarded with another clanking noise. This time it came from much closer, as a small secret cabinet opened up behind the square.

Inside the cabinet were eight bronze keys, each delicately crafted with a map of the world engraved in the top. I took one and wondered where to go next.

Well, the letter told me to proceed counterclockwise, and there was only one leg of the tower left to go, so... I headed northeast. The final leg loomed over me, the moon casting angular shadows from behind it. But I had to keep going. To show them that I really had passed all those tests, and I had what it took to pass one more.

There was no code, math, or riddle here, just a tiny keyhole. I turned the key.

A door slid open in the ground, stone and concrete giving way to a glassy staircase that led into the dark. I shuddered. Then the sound of applause came from down below, and a man walked out to greet me. He looked South Asian, maybe Indian, with enormous glasses and a simple-looking white robe. As I looked closer, though, I saw patterns woven into the fabric. Numbers, equations, math signs--far too many to understand.

"Congratulations," he said with a smile. He spoke with no accent, just the deliberate, precise tone of a totally mastered second (or third? Fourth? Tenth?) language. "You are officially the first to arrive at the School. I'm Dean Bahu, director of student life here. The others will be arriving within the next few hours after their own in-processing, but for now, you must be feeling very jetlagged. Please relax and enjoy yourself."

For the first time since arriving in Paris, I relaxed. I was officially in.

One thing still bothered me, though. I thought back to that secret door behind the magic square on the southeast leg. There were supposed to be seven students at the School, the smartest kids from each continent. So why were there eight keys in the cabinet?