Septemdecim

The halls of the academy are eerily quiet at this hour. The moon's silver glow filters through the arched windows, casting faint shadows that stretch and twist along the stone corridors. My pulse is steady, but I can't shake the feeling that we're being watched.

"You're sure about this?" I whisper, my voice barely above a breath.

"Of course not," Evelyn replies with a mischievous grin. "But that's what makes it exciting."

She moves ahead, leading me down the eastern corridor where the iron gate looms before us—the last physical barrier between us and the underground chambers. It's enormous, its surface carved with swirling sigils of protection. Every student knows this passage is forbidden, but that hasn't stopped Evelyn from trying.

I place a hand against the cold metal, my breath misting against the chill in the air. "How do we get past this?"

Evelyn pulls out a small glass vial filled with a swirling silver liquid. "A little something I borrowed from the Aqua Wing." She tilts the vial over the lock, and the liquid seeps into the mechanism. For a moment, nothing happens—then, the lock crumbles to dust.

I exhale. "Remind me never to underestimate you."

With a shared glance, we slip through the gate and into the tunnel beyond.

The air grows thick with moisture, and the stone walls narrow around us. Dim crystal lanterns embedded in the rock emit a faint blue glow, barely enough to illuminate our path. The ground slopes downward beneath my feet, uneven and damp, and the scent of aged parchment and mineral-rich stone fills my lungs.

"This place is—"

"Creepy?" Evelyn offers.

"I was going to say different'," I mutter, brushing my fingers along the rough walls.

We press forward, winding deeper into the underground. Just as I begin to wonder how much farther we need to go, the space opens up into a small cavern, and at its center stands a massive stone door.

"Found it," Evelyn breathes.

I take a slow step forward, examining the engravings across the door's surface. Ancient symbols and numerical patterns form an intricate puzzle, the locking mechanism unlike anything I've ever seen.

Evelyn kneels beside a worn inscription. "It's a number sequence," she murmurs. "Look."

I crouch beside her, my eyes scanning the carved figures. A set of disjointed equations stretches across the base of the door, some numbers missing entirely.

"What happens if we solve it?" I ask.

Evelyn grins. "Only one way to find out."

She pulls a piece of charcoal from her pocket and begins sketching numbers on the stone. I lean closer, my mind piecing together the logic. The pattern follows a sequence, but something about it feels deliberate—like a hidden message waiting to be uncovered.

I fill in a missing value. Evelyn does the next. Slowly, the numbers take shape.

Then it clicks.

"It's spelling something," I murmur.

Evelyn's gaze flicks up. "What?"

I press my hand against the final inscription and whisper the answer.

"Frinx."

The second the word leaves my lips, the equations glow brilliant gold, their light spreading like veins through the stone. A low, grating rumble shakes the ground, and dust cascades from the cavern ceiling.

Evelyn grips my wrist. "I think you just unlocked it."

My heart pounds as the door groans, its heavy form shifting ever so slightly. A sliver of darkness appears where stone should be. I lean forward, straining to see what lies beyond.

And then—a voice behind me freezes me in place.

"Stop."

The single word sends a jolt down my spine.

I whirl around—and come face to face with Yohan.