Brom shrugged. “I’ve heard reports of the Ra’zac moving from place to place with incredible speed, but this is the first evidence I’ve had of it. It will be almost impossible to find them if they have flying steeds. They aren’t dragons—I know that much. A dragon would never consent to bear a Ra’zac.”

“What do we do? Saphira can’t track them through the sky. Even if she could, we would leave you far behind.”

“There’s no easy solution to this riddle,” said Brom. “Let’s have lunch while we think on it. Perhaps inspiration will strike us while we eat.” Eragon glumly went to his bags for food. They ate in silence, staring at the empty sky.

Once again Eragon thought of home and wondered what Roran was doing. A vision of the burnt farm appeared before him and grief threatened to overwhelm him.What will I do if we can’t find the Ra’zac? What is my purpose then? I could return to Carvahall— he plucked a twig from the ground and snapped it between two fingers—or just travel with Brom and continue my training.Eragon stared out at the plains, hoping to quiet his thoughts.

When Brom finished eating, he stood and threw back his hood. “I have considered every trick I know, every word of power within my grasp, and all the skills we have, but I still don’t see how we can find the Ra’zac.” Eragon slumped against Saphira in despair. “Saphira could show herself at some town. That would draw the Ra’zac like flies to honey. But it would be an extremely risky thing to attempt. The Ra’zac would bring soldiers with them, and the king might be interested enough to come himself, which would spell certain death for you and me.”

“So what now?” asked Eragon, throwing his hands up.Do you have any ideas, Saphira?

No.

“That’s up to you,” said Brom. “This is your crusade.”

Eragon ground his teeth angrily and stalked away from Brom and Saphira. Just as he was about to enter the trees, his foot struck something hard. Lying on the ground was a metal flask with a leather strap just long enough to hang off someone’s shoulder. A silver insignia Eragon recognized as the Ra’zac’s symbol was wrought into it.

Excited, he picked up the flask and unscrewed its cap. A cloying smell filled the air—the same one he had noticed when he found Garrow in the wreckage of their house. He tilted the flask, and a drop of clear, shiny liquid fell on his finger. Instantly Eragon’s finger burned as if it were on fire. He yelped and scrubbed his hand on the ground. After a moment the pain subsided to a dull throbbing. A patch of skin had been eaten away.

Grimacing, he jogged back to Brom. “Look what I found.” Brom took the flask and examined it, then poured a bit of the liquid into the cap. Eragon started to warn him, “Watch out, it’ll burn—”

“My skin, I know,” said Brom. “And I suppose you went ahead and poured it all over your hand. Your finger? Well, at least you showed sense enough not to drink it. Only a puddle would have been left of you.”

“What is it?” asked Eragon.

“Oil from the petals of the Seithr plant, which grows on a small island in the frigid northern seas. In its natural state, the oil is used for preserving pearls—it makes them lustrous and strong. But when specific words are spoken over the oil, along with a blood sacrifice, it gains the property to eat any flesh. That alone wouldn’t make it special—there are plenty of acids that can dissolve sinew and bone—except for the fact that it leaves everything else untouched. You can dip anything into the oil and pull it out unharmed, unless it was once part of an animal or human. This has made it a weapon of choice for torture and assassination. It can be stored in wood, slathered on the point of a spear, or dripped onto sheets so that the next person to touch them will be burned. There are myriad uses for it, limited only by your ingenuity. Any injury caused by it is always slow to heal. It’s rather rare and expensive, especially this converted form.”

Eragon remembered the terrible burns that had covered Garrow.That’s what they used on him, he realized with horror. “I wonder why the Ra’zac left it behind if it’s so valuable.”

“It must have slipped off when they flew away.”

“But why didn’t they come back for it? I doubt that the king will be pleased that they lost it.”

“No, he won’t,” said Brom, “but he would be even more displeased if they delayed bringing him news of you. In fact, if the Ra’zac have reached him by now, you can be sure that the king has learned your name. And that means we will have to be much more careful when we go into towns. There will be notices and alerts about you posted throughout the Empire.”

Eragon paused to think. “This oil, how rare is it exactly?”

“Like diamonds in a pig trough,” said Brom. He amended himself after a second, “Actually, the normal oil is used by jewelers, but only those who can afford it.”

“So there are people who trade in it?”

“Perhaps one, maybe two.”

“Good,” said Eragon. “Now, do the cities along the coast keep shipping records?”

Brom’s eyes brightened. “Of course they do. If we could get to those records, they would tell us who brought the oil south and where it went from there.”

“And the record of the Empire’s purchase will tell us where the Ra’zac live!” concluded Eragon. “I don’t know how many people can afford this oil, but it shouldn’t be hard to figure out which ones aren’t working for the Empire.”