Dorian jerked awake at the sound of a clock chiming, and found himself sweating despite the fierce cold in his bedroom.

It was odd enough that he’d fallen asleep, but the frigid temperature was what struck him as most unusual. His windows were all sealed, his door shut.

And yet his shallow breaths clouded in front of him.

He sat up, his head aching.

A nightmare—of teeth and shadows and glinting daggers. Just a nightmare.

Dorian shook his head, the temperature in the room already increasing. Perhaps it had only been a rogue draft. The nap was just the product of staying up too late last night; the nightmare probably triggered by hearing from Chaol about Celaena’s encounter.

He gritted his teeth. Her job wasn’t without risk—and though he was furious about what had happened, he had a feeling she’d only push him away further if he yelled at her about it.

Dorian shook off the last bit of the cold and walked to his dressing room to change his wrinkled tunic. As he turned, he could have sworn he caught a glimpse of a faint ring of frost around where his body had lain on the couch.

But when he looked back to see it more fully, there was nothing there.

Celaena heard a distant clock chime somewhere—and didn’t quite believe it when she heard the time. She’d been here for three hours. Three hours. The back wall wasn’t like the side wall; it dipped and curved and had closets and alcoves and little study rooms full of mice and dust. And just when she’d been about to draw an X on the wall and call it a day, she noticed the tapestry.

She saw it only because it was the sole bit of decoration she’d encountered along the wall. Considering how the last six months of her life had gone, part of her just knew that it had to mean something.

There was no depiction of Elena, or a stag, or anything lovely and green.

No; this tapestry, woven from red thread so dark it looked black, depicted … nothing.

She touched the ancient strands, marveling at the hue, so deep that it seemed to swallow her fingers in its darkness. The hair on the back of her neck rose, and Celaena put a hand on her dagger as she pulled the tapestry aside. She swore. And swore again.

Another secret door greeted her.

Glancing around the stacks, listening for any footsteps or rustle of clothing, Celaena pushed it open.

A breeze, musty and thick, floated past her from the depths of the spiral stairwell revealed by the open door. The light of her torch reached only a few feet inside, illuminating ornately carved walls depicting a battle.

There was a thin groove in the marble wall, a channel barely three inches deep. It curved along the entire length of the wall, extending beyond the limits of her sight. She swiped her finger in the groove; it was smooth as glass and held a faint residue of something slimy.

A small silver lamp hung from the wall, and she put her torch in its place as she took down the lamp, liquid splashing inside. “Clever,” she murmured.

Smiling to herself, making sure her torch was far enough away, Celaena placed the slender nozzle of the lamp into the groove and tipped. Oil poured out and traveled down the chute. Celaena grabbed her torch and touched it to the wall. Instantly, the groove glowed with fire, providing a thin line of light all the way down the dark and cobwebbed stairwell. A hand on her hip, she stared down, admiring the engraved surface of the walls.

She doubted anyone would come looking for her, but she still put the tapestry back into its original position and took out one of her long daggers. As she descended, the images of battle shifted and moved in the firelight, and she could have sworn that the stone faces turned to watch her go. She stopped looking at the walls.

A breath of cold air brushed her face, and she at last spied the bottom of the stair. It was a dark corridor that smelled of aged and rotting things. A torch lay discarded at the bottom of the step, covered with enough cobwebs to reveal that no one had been down here in a long, long time.

Unless that thing can see in the dark.

She shoved away that thought, too, and picked up the torch, igniting it on the illuminated wall of the stairwell.

Cobwebs hung from the arched ceiling, grazing over the cobblestone floor. Rickety bookcases lined the halfway, the shelves crammed full of books so worn that Celaena couldn’t read the titles. Scrolls and pieces of parchment were stuffed into every nook and cranny or lay unrolled on the sagging wood, as if someone had just walked away from reading them. Somehow, it was more of a tomb than Elena’s resting place.

She walked down the corridor, stopping occasionally to examine the scrolls. They were maps and receipts from kings long since turned to dust.

Castle records. All this walking and fretting, and all you’ve discovered is useless castle records. That’s probably what that creature was after: an ancient king’s grocery bill.

Beginning a chant of truly despicable curses, Celaena waved her torch before her and walked on until a hallway appeared on the left.

It had to lead even lower than Elena’s tomb—but how deep? There was a lantern and a groove in the wall, so Celaena once again lit the spiraling passage. This time, the gray stone depicted a forest. A forest, and—

Fae. It was impossible to miss those delicately pointed ears and elongated canines. The Fae lounged and danced and played music, content to bask in their immortality and ethereal beauty.

No, the king and his cronies couldn’t know about this place, because they certainly would have defaced these carvings by now. Celaena didn’t need a historian to know that this stairwell was old—far older than the one through which she had just descended, perhaps even older than the castle itself.

Why had Gavin picked this site to build his castle? Had there been something here before?

Or something beneath it worth hiding?

A cold sweat slithered down her spine as she peered into the stairwell. Against all odds, another breeze wafted up from below. Iron. It smelled like iron.

The images on the walls flickered as she descended the spiral staircase. When she at last reached the bottom, she took a shallow breath and ignited a torch from a nearby bracket. She was in a long hallway paved in gray stones. There was only one door in the center of the left-hand wall, and no exit save for the stairs behind her.

She scanned the hall. Nothing. Not even a mouse. After observing for another moment, she stepped down it, igniting the few torches on the wall as she went.

The iron door was unremarkable, though undeniably impenetrable. Its studded surface was like a slab of starless sky.

Celaena stretched out a hand, but stopped before her fingers could graze the metal.

Why was it made entirely of iron?

Iron was the one element immune to magic; she remembered that much. There had been so many kinds of magic-wielders ten years ago—people whose power was believed by some to have long ago originated from the gods themselves, despite the King of Adarlan’s claim that magic was an affront to the divine. Wherever it came from, magic had countless variations: abilities to heal, to shape-shift, to summon flame or water or storm, to encourage the growth of crops and plants, to glimpse the future, and on and on. Most of those gifts had been watered down over the millennia, but for some rare strong ones, when they held on to their power too long, the iron in their blood caused fainting spells. Or worse.

She had seen hundreds of doors in the castle—doors of wood, of bronze, of glass—but never one of solid iron. This one was ancient, from a time when an iron door meant something. So was this supposed to keep someone out—or to keep something in?