She sighed, pushing back off the battlement and hopping onto the wall walk. Then she leaned back against one of the merlons. To the side, OreSeur trotted up the wall steps and approached. Once again, he went down onto his haunches, watching patiently.

For better or for worse, Vin's simple life of starvation and beatings was gone. Elend's fledgling kingdom was in serious danger, and she'd burned away the last of his atium trying to keep herself alive. She'd left him exposed—not just to armies, but to any Mistborn assassin who tried to kill him.

An assassin like the Watcher, perhaps? The mysterious figure who had interfered in her fight against Cett's Mistborn. What did he want? Why did he watch her, rather than Elend?

Vin sighed, reaching into her coin pouch and pulling out her bar of duralumin. She still had the reserve of it within her, the bit she'd swallowed earlier.

For centuries, it had been assumed that there were only ten Allomantic metals: the four base metals and their alloys, plus atium and gold. Yet, Allomantic metals always came in pairs—a base metal and an alloy. It had always bothered Vin that atium and gold were considered a pair, when neither was an alloy of the other. In the end, it had turned out that they weren't actually paired; they each had an alloy. One of these—malatium, the so-called Eleventh Metal—had eventually given Vin the clue she'd needed to defeat the Lord Ruler.

Somehow Kelsier had found out about malatium. Sazed still hadn't been able to trace the "legends" that Kelsier had supposedly uncovered teaching of the Eleventh Metal and its power to defeat the Lord Ruler.

Vin rubbed her finger on the slick surface of the duralumin bar. When Vin had last seen Sazed, he'd seemed frustrated—or, at least, as frustrated as Sazed ever grew—that he couldn't find even hints regarding Kelsier's supposed legends. Though Sazed claimed he'd left Luthadel to teach the people of the Final Empire—as was his duty as a Keeper—Vin hadn't missed the fact that Sazed had gone south. The direction in which Kelsier claimed to have discovered the Eleventh Metal.

Are there rumors about this metal, too? Vin wondered, rubbing the duralumin. Ones that might tell me what it does?

Each of the other metals produced an immediate, visible effect; only copper, with its ability to create a cloud that masked an Allomancer's powers from others, didn't have an obvious sensory clue to its purpose. Perhaps duralumin was similar. Could its effect be noticed only by another Allomancer, one trying to use his or her powers on Vin? It was the opposite of aluminum, which made metals disappear. Did that mean duralumin would make other metals last longer?

Movement.

Vin just barely caught the hint of shadowed motion. At first, a primal bit of terror rose in her: Was it the misty form, the ghost in the darkness she had seen the night before?

You were just seeing things, she told herself forcefully. You were too tired. And, in truth, the glimmer of motion proved too dark—too real—to be the same ghostly image.

It was him.

He stood atop one of the watchtowers—not crouching, not even bothering to hide. Was he arrogant or foolish, this unknown Mistborn? Vin smiled, her apprehension turning to excitement. She prepared her metals, checking her reserves. Everything was ready.

Tonight I catch you, my friend.

Vin spun, throwing out a spray of coins. Either the Mistborn knew he'd been spotted, or he was ready for an attack, for he easily dodged. OreSeur hopped to his feet, spinning, and Vin whipped her belt free, dropping her metals.

"Follow if you can," she whispered to the kandra, then sprang into the darkness after her prey.

The Watcher shot away, bounding through the night. Vin had little experience chasing another Mistborn; her only real chance to practice had come during Kelsier's training sessions. She soon found herself struggling to keep up with the Watcher, and she felt a stab of guilt for what she had done to OreSeur earlier. She was learning firsthand how difficult it was to follow a determined Mistborn through the mists. And she didn't have the advantage of a dog's sense of smell.

She did, however, have tin. It made the night clearer and enhanced her hearing. With it, she managed to follow the Watcher as he moved toward the center of the city. Eventually, he let himself drop down toward one of the central fountain squares. Vin fell as well, hitting the slick cobblestones with a flare of pewter, then dodging to the side as he threw out a handful of coins.

Metal rang against stone in the quiet night, coins plinging against statues and cobblestones. Vin smiled as she landed on all fours; then she bounded forward, jumping with pewter-enhanced muscles and Pulling one of the coins up into her hand.

Her opponent leaped backward, landing on the edge of a nearby fountain. Vin landed, then dropped her coin, using it to throw herself upward over the Watcher's head. He stooped, watching warily as she passed over him.

Vin caught of one of the bronze statues at the center of the fountain itself and pulled herself to a stop atop it. She crouched on the uneven footing, looking down at her opponent. He stood balanced on one foot at the edge of the fountain, quiet and black in the churning mists. There was a. . .challenge in his posture.

Can you catch me? he seemed to ask.

Vin whipped her daggers out and jumped free of the statue. She Pushed herself directly toward the Watcher, using the cool bronze as an anchor.

The Watcher used the statue as well, Pulling himself forward. He shot just beneath Vin, throwing up a wave of water, his incredible speed letting him skid like a stone across the fountain's still surface. As he jumped clear of the water, he Pushed himself away, shooting across the square.

Vin landed on the fountain lip, chill water spraying across her. She growled, jumping after the Watcher.

As he landed, he spun and whipped out his own daggers. She rolled beneath his first attack, then brought her daggers up in a two-handed double jab. The Watcher jumped quickly out of the way, his daggers sparkling and dropping beads of fountain water. He had a lithe power about him as he came to rest in a crouch. His body looked tense and sure. Capable.

Vin smiled again, breathing quickly. She hadn't felt like this since. . .since those nights so long ago, when she'd sparred with Kelsier. She remained in a crouch, waiting, watching the mist curl between her and her opponent. He was of medium height, had a wiry build, and he wore no mistcloak.

Why no cloak? Mistcloaks were the ubiquitous mark of her kind, a symbol of pride and security.

She was too far away to distinguish his face. She thought she saw a hint of a smile, however, as he jumped backward and Pushed against another statue. The chase began again.

Vin followed him through the city, flaring steel, landing on roofs and streets, Pushing herself in great arcing leaps. The two bounded through Luthadel like children on a playground—Vin trying to cut off her opponent, he cleverly managing to stay just a little bit ahead of her.

He was good. Far better than any Mistborn she had known or faced, save perhaps for Kelsier. However, she'd grown greatly in skill since she'd sparred with the Survivor. Could this newcomer be even better? The thought thrilled her. She'd always considered Kelsier a paradigm of Allomantic ability, and it was easy to forget that he'd had his powers for only a couple of years before the Collapse.

That's the same amount of time that I've been training, Vin realized as she landed in a small, cramped street. She frowned, crouching, remaining still. She'd seen the Watcher fall toward this street.

Narrow and poorly maintained, the street was practically an alleyway, lined on both sides by three- and four-story buildings. There was no motion—either the Watcher had slipped away or he was hiding nearby. She burned iron, but the iron-lines revealed no motion.

However, there was another way. . ..

Vin pretended to still be looking around, but she turned on her bronze, flaring it, trying to pierce the coppercloud that she thought might be close.

And there he was. Hiding in a room behind the mostly closed shutters of a derelict building. Now that she knew where to look, she saw the bit of metal he'd probably used to jump up to the second story, the latch he must have Pulled on to quickly close the shutters behind him. He'd probably scouted this street beforehand, always intending to lose her here.

Clever, Vin thought.

He couldn't have anticipated her ability to pierce copperclouds. But, attacking him now might give away that ability. Vin stood quietly, thinking of him crouching above, tensely waiting for her to move off.

She smiled. Reaching inside, she examined the duralumin reserve. There was a possible way to discover if burning it created some change in the way she looked to another Mistborn. The Watcher was likely burning most of his metals, trying to determine what her next move would be.

So, thinking herself incredibly clever, Vin burned the fourteenth metal.

A massive explosion sounded in her ears. Vin gasped, dropping to her knees in shock. Everything grew bright around her, as if some crack of energy had illuminated the entire street. And she felt cold; frigidly, stunningly cold.

She moaned, trying to make sense of the sound. It. . .it wasn't an explosion, but many explosions. A rhythmic thudding, like a drum pounding just beside her. Her heart-beat. And the breeze, loud as a howling wind. The scratchings of a dog searching for food. Someone snoring in their sleep. It was as if her hearing had been magnified a hundred times.

And then. . .nothing. Vin fell backward against the cobblestones, the sudden rush of light, coldness, and sound evaporating. A form moved in the shadows nearby, but she couldn't make it out—she couldn't see in the darkness anymore. Her tin was. . .

Gone, she realized, coming to. My entire store of tin has been burned away. I was. . .burning it, when I turned on the duralumin.

I burned them both at once. That's the secret. The duralumin had burned away all her tin in a single, massive burst. It had made her senses amazingly acute for a very short time, but had stolen away her entire reserve. And, looking, she could see that her bronze and her pewter—the other metals she'd been burning at the time—were gone as well. The onrush of sensory information had been so vast that she hadn't noticed the effects of the other two.

Think about it later, Vin told herself, shaking her head. She felt like she should be deafened and blinded, but she wasn't. She was just a bit stunned.

The dark form moved up beside her in the mists. She didn't have time to recover; she pushed herself to her feet, stumbling. The form, it was too short to be the Watcher. It was. . .

"Mistress, do you require assistance?"

Vin paused as OreSeur padded up to her, then sat on his haunches.

"You. . .managed to follow," Vin said.

"It was not easy, Mistress," OreSeur said flatly. "Do you require assistance?"

"What? No, no assistance." Vin shook her head, clearing her mind. "I guess that's one thing I didn't think of by making you a dog. You can't carry metals for me now."

The kandra cocked his head, then padded over into an alleyway. He returned a moment later with something in his mouth. Her belt.

He dropped it by her feet, then returned to his waiting position. Vin picked up the belt, pulling off one of her extra metal vials. "Thank you," she said slowly. "That is very. . .thoughtful of you."

"I fulfill my Contract, Mistress," the kandra said. "Nothing more."

Well, this is more than you've ever done before, she thought, downing a vial and feeling her reserves return. She burned tin, restoring her night vision, releasing a veil of tension from her mind; since she'd discovered her powers, she'd never had to go out at night in complete darkness.