The creature pushed a gnarled hand against its abdomen, panting through those brown, broken teeth as it looked at her—looked at her with such hatred that she couldn’t move. It was such a human expression …

“What are you?” She gasped, swinging Damaris as she took another step back.

But it suddenly began clawing at itself, tearing at the dark robes, pulling out its hair, pushing against its skull, as if it would reach in and rip something out. And the shrieks it made, the rage and despair—

The creature had been in the castle hallway.

Which meant …

This thing, this person—it knew how to use the Wyrdmarks, too. And with its unnatural strength, no mortal barrier would keep it contained.

The creature tipped its head back, and its animal eyes settled on her again. Fixating. A predator anticipating the taste of its prey.

Celaena turned and ran like hell.

Dorian had just passed through the third door when he heard the scream of something not human. A series of crashing noises filled the passage, and the bellowing was cut short with each slam.

“Celaena?” Dorian yelled in the direction of the commotion.

Another slam.

“Celaena!”

Then—“Dorian, run!”

The highpitched shriek that followed Celaena’s command shook the walls. The torches sputtered.

Dorian drew his rapier as Celaena came flying up the stairs, blood leaking from her face, and slammed the iron door shut behind her. She raced toward him, a sword in one hand, a dagger in the other. The amulet on her neck glowed blue, like the hottest fire.

Celaena was upon him in a second. The iron door burst open behind them, and—

The thing that came out was not of this earth—it couldn’t be. It looked like something that used to be a man, but was twisted and dried and broken, with hunger and madness written on every protruding bone in its body. Gods. Oh, gods. What had she awoken?

They sprinted down the hall, and Dorian swore as he beheld the steps up to the next door. The time it would take for them to climb the stairs …

But Celaena was fast. And months of training had made her strong. To his eternal humiliation, as they hit the bottom of the stairs, she grasped him by the collar of his tunic, half-hauling him up the steps. She hurled him into the hallway beyond the threshold.

Behind them, the thing shrieked. Dorian turned in time to see its broken teeth glistening as it leapt up the stairs. Lightning swift, Celaena slammed the iron door shut in the creature’s face.

Only one more door—he could picture the landing that led back to the first hallway, then that spiral staircase, then the second staircase, and—

What then, when they reached the main library? What could they do against this thing?

As Dorian saw the naked terror on Celaena’s face, he knew she wondered the same.

Celaena threw Dorian into the hallway and then hurled herself backward, slamming into the last iron door that separated the thing’s lair from the rest of the library. She put her weight into it and saw stars as the creature barreled into the other side. Gods, it was strong—strong and wild and unyielding …

For a moment, she stumbled away, and it tried to fling open the door. But Celaena lunged, throwing her back against it.

Its hand caught in the door and the creature bellowed, latching its claws into Celaena’s shoulder as she pushed and pushed. Blood ran from her nose, mingling with the blood running down her shoulders. The claws dug in farther.

Dorian rushed to the door, bracing his back against it. He panted, gaping at her.

They had to seal the door. Even if this thing was intelligent enough to know the Wyrdmarks, they had to buy some time for themselves. She had to give Dorian enough time to get away. They would run out of strength soon, and the thing would break through and kill them and whoever else got in its path.

There had to be a lock somewhere, some way to shut it in, to slow it down just for a moment …

“Push,” she breathed to Dorian. The creature gained an inch, but Celaena shoved hard, drawing on the strength of her legs. It roared again, so loudly that she thought blood would pour from her ears. Dorian swore viciously.

She glanced at him, not even feeling the pain of the talons embedded in her skin. Sweat ran down Dorian’s brow as—as—

The metal began to heat along the edge of the door, glowing red, then fizzing—

Magic was here; magic was working right now, trying to seal the door against the creature. But it wasn’t coming from her.

Dorian’s eyes were scrunched in concentration, his face deathly pale.

She’d been right. Dorian did have magic. This was the information Yellowlegs had wanted to sell to the highest bidder, sell to the king himself. It was knowledge that could change everything. It could change the world.

Dorian had magic.

And if he didn’t stop, he was going to burn himself out on the iron door.

The door suffocated Dorian. He was in a coffin, a coffin with no air. His magic couldn’t breathe. He couldn’t breathe.

Celaena swore as the creature gained ground. Dorian didn’t even know what he was doing, only that he needed to seal this door. His magic had chosen the method. He pushed with his legs, pushed with his back, pushed his magic to the breaking point as he sought to weld the door. Spinning, heat, strangling …

The magic slipped from him.

The creature pushed hard, sending Dorian staggering forward. But Celaena threw herself harder against the door as he regained his balance.

Celaena’s blade lay a few feet away, but what good was a sword?

They had no hope of escaping with their lives.

Celaena’s eyes met with his, the question all too visible on her bloodied face:

What have I done?

Still gripped by the creature’s talons, Celaena couldn’t even move as Dorian made a sudden lunge for Damaris. The creature tried again to break free, and the prince swung, making direct contact with its wrist. Its shriek penetrated her bones, but the door slammed shut completely. Celaena stumbled, the beast’s dismembered hand protruding from her shoulder, but she shoved back against the door as the creature again launched itself at it.

“What the hell is it?” Dorian barked, throwing his weight back against the iron.

“I don’t know,” Celaena breathed. Not having the luxury of a healer, she ripped the filthy hand from her shoulder, biting down on her scream. “It was down there,” she panted. Another thud from behind the door. “You can’t seal that door with magic. We need to—need to seal this another way.” And find something that would outsmart whatever unlocking spells this creature knew—some way to keep it from getting out. She choked on the blood running from her nose into her mouth, and spat it onto the floor. “There is a book—The Walking Dead. It’ll have the answer.”

Their eyes met and held. A line stretched taut between them—a moment of trust, and a promise of answers from both of them.

“Where’s the book?” Dorian asked.

“In the library. It’ll find you. I can hold this for a few moments.”

Not needing it to make sense, Dorian bolted upstairs. He ran through stack after stack, his fingers reading the titles, faster and faster, knowing each second drained her strength. He was about to bellow his frustration when he ran past a table and beheld a large black volume resting upon its surface.

The Walking Dead.

She had been right. Why was she always right, in her own odd way? He grabbed the book and hurtled to the secret chamber. She had shut her eyes, and her teeth were red with her own blood as she gritted them.

“Here,” Dorian said. Without needing her to ask, he shoved himself into the door as she dropped to the floor and grabbed the book to her. Her hands trembled as she flipped a page, then another, and another. Her blood splattered onto the text.

“‘To bind or to contain,’” she read aloud. Dorian peered down at the dozens of symbols on the page.

“This will work?” he asked.

“I hope so,” she wheezed, already moving, clutching the open book in one hand. “Once the spell is cast, just passing over that threshold will hold it in place long enough to kill it.” She dipped her fingers into the wounds on her chest, and he could only gape as she made the first mark, and then the second, turning her battered body into an inkwell as she drew mark after mark around the door.

“But for it to pass over the threshold,” Dorian panted, “we’d have to—”

“Open the door,” she finished for him, nodding.

He shifted so she could reach to draw above his head, their breath mingling.

Celaena let out a long breath as she made the last mark, and suddenly, they glowed a faint blue. He held himself against the door, even as he felt the iron go rigid.

“You can let go,” she breathed, angling the sword. “Let go, and get the hell behind me.”

At least she didn’t insult him by telling him to flee.

With a final breath, he leapt away.

The creature slammed into the door, flinging it open.

And, just like she had said, it froze on the threshold, its animalistic eyes wild as its head jutted out into the hall. There was a pause then, a pause during which Dorian could have sworn that Celaena and the creature looked at each other—and its wildness calmed, just for a moment. Just for a moment, and then Celaena moved.

The sword flashed in the torchlight, and there was the squish of flesh and crunch of bone. The neck was too thick to sever in one blow, so before Dorian could draw another breath, she struck again.

The head hit the ground with a thud, black blood spraying from the severed neck—from the body that still stood paralyzed in the doorway.

“Shit,” Dorian breathed. “Shit.”

Celaena moved again, slamming her sword down onto the head, skewering it, as if she thought it could still bite.

Dorian was still spewing a steady stream of curses as Celaena reached out to the bloody marks around the door and swiped a finger through one of them.

The creature’s headless body collapsed, the holding spell broken.

It had barely finished falling before Celaena made four strikes: three to sever the emaciated torso in two, and a fourth to stab through where its heart would be. His bile rose up again as she angled her blade a fifth time, prying open the chest cavity of the creature.

Whatever she saw made her face go even paler. Dorian didn’t want to look.

With grim efficiency, she kicked the too-human head through the threshold, sending it knocking into the withered corpse of the creature. Then she shut the iron door and traced a few more marks over the threshold that glowed and then faded.

Celaena faced him, but Dorian looked at the door again, now sealed.

“How long does that—that spell hold?” He almost choked on the word.

“I don’t know,” she said, shaking her head. “Until I remove the marks, I think.”

“I don’t think we can let anyone else know about this,” he said carefully.

She laughed, a bit wildly. Telling others, even Chaol, would mean answering difficult questions—questions that could earn them both a trip to the butchering block.

“So,” Celaena said, spitting blood onto the stones, “do you want to explain yourself first, or should I?”

Celaena went first, because Dorian desperately needed to change his filthy tunic, and talking seemed like a good idea while he stripped naked in his dressing room. She sat on his bed, not looking much better herself—which was why they’d taken the dark servants’ passages back to his tower.

“Beneath the library stretches an ancient dungeon, I think,” Celaena said, trying to keep her voice as soft as possible. She caught a gleam of golden skin through the half-open door to his dressing room, and looked away. “I think … I think someone kept the creature in there until it broke out of its cell. It’s been living under the library ever since.”