“Are we going to the river?” Aaron asked in a half whisper. The air of the tunnels was getting damper. They’d passed several of the rooms of other apprentice groups, only darkness showing under the doors. The Magisterium was asleep.

The rivers that ran through the school were its transportation artery. They carried students from classrooms to gates that led outside, to the Refectory and back to their rooms. Small boats moved on the rivers, powered by magic and assisted by water elementals. As Call, Aaron, and Tamara approached the water, the cave air grew colder, and Call could hear the rushing sound of the river.

Aaron and Tamara were muttering about whether Call was dragging them off to take a boat. The corridor opened out onto a pebbled underground beach. Phosphorescent moss clung to the walls and roof, lighting the space. Eyeless fish swam around under the water’s surface.

“Warren!” Call called. “Warren!”

Aaron and Tamara exchanged a look. It was clear they thought Call had lost his mind.

“Maybe he needs sleep,” said Tamara.

“Maybe he needs food,” said Aaron.

“Warren!” Call shouted again. “‘The end is closer than you think!’”

“Lizards don’t come when you call them,” Tamara said. “Let’s get out of here, Call —”

Something scrambled down from the rocky overhang above them. There was a flash of fire, light on scales. Red eyes gleamed in the dimness. What looked like a tiny Komodo dragon with a beard and back ridge made out of fire crawled toward them across the rocks.

“Warren?” said Call.

“He really did come.” Aaron sounded impressed. “Awesome, Call.”

“Sneaking.” Warren looked annoyed. “Sneaking and bothering Warren. What do you want, mage students?”

“We want you to take us to the sleeping elementals. The ones bound by the Magisterium,” Call said.

“Right now?” Tamara demanded, whirling on Call. “I thought we were going to sleep!”

“Yes, sleep. Sneaking too dangerous,” Warren said. “Tunnels too deep.”

“You owe us, Warren,” Call said. “We saved your life. Don’t you remember?”

“I pay you back already,” Warren muttered. “I warn you. Ultima Forsan.”

“That’s not help,” Call said. He knew what Ultima Forsan was: a Latin phrase that had been carved over the Enemy of Death’s resting-place. It meant the end is closer than you think. He just didn’t see how it was a warning in any useful way. “Taking us to the elementals, that would be helpful.”

“Maybe you don’t know how to get there,” Aaron taunted the little lizard. Although he was the one who’d yawned back at the library, now his eyes glittered and he didn’t look tired in the least. Aaron was someone who didn’t like talking about doing things half as much as he liked actually doing them. “Is that the problem? Maybe you don’t know that much about the Magisterium after all.”

Warren’s red eyes whirled. “I know,” he said. “I know everything. But this is dangerous, little mage students. Dangerous business. I could take you, but you will have to trick the guardian.”

“The guardian?” Tamara asked in tones of dread.

Call also would have liked some more clarification, but Warren, apparently deciding that his half of their conversation was over, sprang toward a shining mica wall and ran halfway up, before dashing toward the entrance to the other cavern.

“Follow that lizard!” Call announced, going after him.

Tamara groaned, but she followed.

He forgot that letting Warren lead you through the caves of the Magisterium — including some passageways that might never have been used by a single mage before them — was a frustrating and sometimes terrifying endeavor. The lizard led them along naturally forming cliffs and past lakes of what appeared to be boiling mud. He guided them into and out of rooms where they nearly choked on the sulfur smell and where they had to duck to avoid being scraped by the pointed ends of stalactites.

Call wasn’t sure how far they’d walked when his leg started really hurting — the kind of burning muscle pain that was only going to get worse. He felt stupid for suggesting they do this, stupid for thinking he could walk this far. But he couldn’t ask Warren to stop — the lizard was too far ahead of them, leaping from rock formation to rock formation, the crystals on his back ablaze.

And if Tamara and Aaron paused to wait for him, Warren might sprint ahead, leaving them lost in the caves. It had happened before.

Experimentally, Call drew on air magic, pushing slightly. He remembered the way Alastair had sent Call up the long winding steps of the Collegium. He remembered how he’d made his own way down them. All he had to do was concentrate and push.

Call went up into the air — fast enough that he had to bite the side of his cheek to keep from crying out — but after a moment, he was able to steady himself. He was floating just a little bit above the ground and none of the weight was on his leg. He felt amazing.

He pushed himself along with his mind, no longer stumbling like Aaron or Tamara did. He glided over the earth as though this was the way he was meant to walk. As they went along, the passages curling deeper into the mountain, the walls became smoother, the ground under their feet polished. It was as if they were making their way down the hallway of a museum. The doors set into the stone on either side were elegant, decorated with alchemical symbols and alphabets that Call didn’t know.

At last, Warren stopped in front of a massive door made from the five metals of the Magisterium — iron, copper, bronze, silver, and gold.

“Here, mage students. Here is the locked door in the way of the way. The guardian is here. You must face her to go farther.”

“What do we do?”

“Answer her riddles,” Warren said, and, flicking out his tongue to nab a cave bug that Call hadn’t seen until the lizard scooped it up, raced off along the ceiling. “Riddle her answers!” he called back before he disappeared.

“Crap,” Aaron said. “This always happens. I hate riddles.”

Tamara looked as though she was forcibly swallowing the words I knew it and not much liking their taste.

“Do we just knock?” Call lifted his fist and then hesitated.

“I’ll do it.” Tamara pounded on the door. “Hello? We’re students and we’ve come to do a project —”