With a shrug, Aaron followed.

“Well, I did promise him my gum,” Tamara said, jogging after them.

They followed Warren though a sulfur-streaked hall, orange and yellow and weirdly smooth on all sides — Call felt as though they were walking through the throat of some enormous giant. The floor was unpleasantly moist with reddish lichen, thick and spongy. Aaron nearly tripped, and Call’s feet sank into it, sending the ball of water wobbling as he steadied himself. Tamara stabilized it with a flick of her fingers as they passed into a cavern whose walls were covered with crystalline formations that looked like icicles. A huge mass of crystals hung from the center of the ceiling like a chandelier, glowing faintly.

“This isn’t the way we came,” Aaron complained, but Warren didn’t pause, except to take a bite out of one of the dangling crystals as he went by it. He bypassed all the obvious exits and headed straight for a small dark hole, which turned out to be an almost lightless tunnel. They had to get on their knees and crawl, the globe of water wobbling precariously between them. Sweat was running down Call’s back from the cramped position, his leg was killing him, and he’d begun to worry that Warren was leading them in the totally wrong direction.

“Warren —” he started.

He broke off as the passageway suddenly widened out into a vast chamber. He staggered slowly to his feet, his bad leg punishing him for pushing it so hard. Tamara and Aaron followed, looking pale with the effort of both crawling and holding the water steady at the same time.

Warren scuttled toward an archway leading out. Call followed as fast as his leg would allow.

He was so distracted by the effort that he didn’t notice when the air became warmer, filling with the smell of something burning. It wasn’t until Aaron exclaimed, “We’re been here before — I recognize the water,” that he looked up and saw that they were back in the room with the smoking orange stream and the huge vines that hung down like tendrils.

Tamara exhaled with clear relief. “This is great. Now we just —”

She broke off with a cry as a creature rose out of the smoking stream, making her stumble back and Aaron yell out loud. The ball of water that had hung between them crashed to the floor. The water sizzled as if it had been dumped onto a hot skillet.

“Yes,” said Warren. “Just like I was bid. He told me to bring you back, and now you are here.”

“He told you,” Tamara echoed.

Call stared openmouthed at the huge being rising out of the stream, which had started to boil, huge red and orange bubbles appearing on the surface with the ferocity of lava. The creature was clumped and dark and stony, as if it were made out of shards of jagged rock, but it had a human face, a man’s face, the planes seemingly cut from granite. Its eyes were just holes into darkness.

“Greetings, Iron Mages,” it said, voice echoing as though the thing spoke from some great distance. “You are far from your Master.”

The apprentices were speechless. Call could hear Tamara’s breath rasping in the quiet.

“Have you nothing to say to me?” The creature’s granite mouth moved: It was like watching stone fissure and split apart. “I was once like you, children.”

Tamara made a horrible sound, half sob and half gasp. “No,” she said. “You can’t be one of us — you can’t still speak. You …”

“What is it?” Call hissed. “What is it, Tamara?”

“You’re one of the Devoured,” Tamara said, her voice breaking. “Consumed by an element. Not human anymore….”

“Fire,” the thing breathed. “I became fire long ago. I gave myself to it, and it to me. It burned away what was human and weak.”

“You’re immortal,” Aaron said, his eyes looking very big and green in his pale, grimy face.

“I am so much more than that. I am eternal.” The Devoured leaned close to Aaron, close enough that Aaron’s skin began to flush, the way skin pinkens when someone stands close to a fire.

“Aaron, don’t!” Tamara said, taking a step forward. “It’s trying to burn you, absorb you. Get away from it!”

Her face shone in the flickering light, and Call realized there were tears on her cheeks. He thought suddenly of her sister, consumed by elements, doomed.

“Absorb you?” The Devoured laughed. “Look at you, little flickering sparks, barely grown. Not much life to be squeezed out of you.”

“You must want something from us,” Call said, hoping the Devoured would swing its attention away from Aaron. “Or you wouldn’t have bothered to show yourself.”

The thing turned to him. “Master Rufus’s surprise apprentice. Even the rocks have whispered of you. The greatest of the Masters has chosen strangely this year.”

Call couldn’t believe it. Even the Devoured knew about his crappy entrance scores.

“I see through the masks of skin you wear,” the Devoured continued. “I see your future. One of you will fail. One of you will die. And one of you is already dead.”

“What?” Aaron’s voice rose. “What does that mean, ‘already dead’?”

“Don’t listen to it!” Tamara cried. “It’s a thing, not human —”

“Who would desire to be human? Human hearts break. Human bones shatter. Human skin can tear.” The Devoured, already close to Aaron, reached to touch his face. Call leaped forward as fast as his leg would let him, knocking into Aaron, sending them both tumbling against one of the walls. Tamara whirled to face the Devoured, her hand raised. A swirling mass of air bloomed in her palm.

“Enough!” roared a voice from the archway.

Master Rufus stood there, forbidding and terrible, power seeming to pour off of him.

The thing took a step back, flinching. “I mean no harm.”

“Begone,” said Master Rufus. “Leave my apprentices be or I will dispel you as I would any elemental, no matter who you once were, Marcus.”

“Don’t call me by a name that is no longer mine,” the Devoured said. Its gaze fell on Call, Aaron, and Tamara as it subsided back to the sulfurous pool. “You three I will see again.” It disappeared in a ripple, but Call knew it still remained beneath the surface somewhere.

Master Rufus looked momentarily shaken. “Come along,” he said, ushering his apprentices through a low archway. Call looked back for Warren, but the elemental was gone. Call was briefly disappointed. He wanted to scream at Warren for betraying them — and also to disinvite him from his bedroom forever. But if Master Rufus saw Warren, it would be obvious that Call was the one who’d stolen him from Rufus’s office, so maybe it was good he was gone.

They walked for a while in silence.

“How did you know to come find us?” Tamara asked finally. “That something bad was happening?”

“You don’t think I’d let you wander the depths of the Magisterium unwatched, do you?” said Rufus. “I sent an air elemental to follow you. It reported back to me once you had been drawn into the cavern of the Devoured.”

“Marcus — the Devoured — told us some … he told us our futures,” Aaron said. “What did that mean? Was that — was the Devoured really once an apprentice like us?”