“Almost never. Breathe with me.” She inhales, and I fill my lungs with her. “This part of the forest doesn’t show up on GPS maps or locators,” she says, exhaling. “The trees shield us from satellites, and we have a bit of technology of our own that ensures we remain undercover. Anybody who wanders back here is lost…or trying to find us. But we’re prepared for that. Otherwise, most of Keystone is underground or built high into the trees.” She rubs my back. “Breathe.”

We inhale and exhale together, and she stays by my side until my heart rate slows and the memories are safely tucked away. Squinting up through tears, I stare at the tips of trees disappearing into the sky, unable to discern any structures. “Do I have to learn to climb trees?” My muscles tense.

Allard laughs and helps me to my feet. “No. We have stairs. But we’ll explore those another day, too. This way.”

We walk for a few more minutes in silence until she stops in a seemingly random place and crouches down. “Today, we’re going to focus on the underground. This is the Vault.” She brushes away dirt and leaves from the forest floor to expose a trapdoor. Swiveling up a round, rusted metal dial, she reveals a combination lock hidden beneath it.

“This access code changes daily and is equated from the number of folds in the origami displayed in the Atrium—the Keystone cafeteria—at breakfast,” she says, turning the knob to a sequence of numbers so quickly I can’t register them. “But the Atrium isn’t open this time of year… There’s also a master access code. That’s one of the secrets you’ll learn once you’re initiated.”

With a click, a handle pops up.

“Here we go,” she says, pulling open the trapdoor.

I peer over her shoulder down mossy stone steps into a dark tunnel.

“And don’t forget to breathe. There’s plenty of space down here. I promise.” She starts down, and, swallowing the perma-lump in my throat, I follow close behind, focusing on filling my lungs as we descend past mud walls teeming with ferns.

“Pull the door down behind you, please,” she says as our heads disappear below the earth.

Panic knotting my shoulders, I tug on the lid, blotting out daylight above us. To my relief, lanterns lining the walls at the bottom of the steps illuminate as soon as the door clicks shut. When we reach the base of the stairs, three identical stone tunnels, all with domed ceilings and lined with flickering lanterns, jut in different directions. She’s right. It’s much bigger down here than I could have imagined, and I exhale relief.

“What is this place?” I ask, my vision slowly adjusting to the dim light.

Allard heads down the tunnel to our right.

“A treasure chest of sorts.” Her voice floats back to me, and I scramble to keep up. “This is where we keep our loot.” She laughs. “And it’s where we study. Disconnects have been adding on to it for over a century. It’s like a secret passageway to every city in the world. Behind each door is a replica of a museum containing both authentic and fake works—including 3-D printed forgeries that have rewritten history. It was never meant to be a maze, but as tunnels have been added, it’s turned into a labyrinth of twists and turns. The true number of galleries and treasures hidden down here is one of Keystone’s most guarded secrets.”