The boy took the guide-stone. “It wasn’t her fault,” he said, sounding resentful. “Or any of the guards’. That elemental came from somewhere else.”

“So go tell them that,” said Tamara.

Clutching the guide-stone, the boy stepped out into the corridor. He slammed the door behind him, and Call heard the tumblers of a dozen locks as they slid into place.

“Better scram,” the boy said, glancing briefly over the three of them, and then headed off down the hall.

When the guard was out of sight, Call fumbled the key out of his pocket.

There was a spot in the huge door into which it fit neatly, and when it was placed there, an entire tracery of symbols began to glow all over the door. Words Call had not seen before revealed themselves: Neither flesh nor blood, but spirit. As Call was puzzling over that, the door opened, swinging inward.

They headed inside, passing quickly through the antechamber and into the dark red corridor. It was short, leading to a second, massive set of doors that went up and up, reaching over Call’s head, the size of the doors of an enormous cathedral.

But there was a spot in them, too, a tiny hole, almost too small to notice. Call swallowed and fit the bronze key into the spot. The second set of doors opened with a groan.

They stepped through.

Call didn’t know what to expect, but the sudden heat of the room beyond surprised him. The air was heavy and smelled sour and metallic. It felt like a place where a huge fire was blazing, but no fire was visible. He could hear the rush of water in the distance and the roar of flames, much closer. Arched doorways in the stone led in five different directions. Chiseled in the rock were familiar words: Fire wants to burn, water wants to flow, air wants to rise, earth wants to bind, chaos wants to devour.

“Which way?” Call asked.

Aaron shrugged, then spun around with one arm out, letting himself point randomly, like a weather vane. “There,” he said when he’d stopped. The arch he was pointing toward seemed to be much the same as the others.

“Warren?” Call called under his breath. It seemed like a long shot that the little lizard would hear them down there, but Warren had shown up in strange places and at odd times before. “Warren, we could really use your help.”

“I don’t know about that,” Tamara said, heading in the direction Aaron had picked. “I don’t trust him.”

“He’s not so bad,” Call said, but he couldn’t help thinking of how Warren had led them to Marcus, Master Rufus’s former Master, now one of the Devoured, drawn into the element of fire by using its power too much. Still, Marcus hadn’t hurt them. He’d just been scary.

It was dim beyond the archway, less a corridor than an empty space of tumbled stone with a path cutting through it, leading into further darkness. A torch was embedded in one wall, burning greenly; Aaron took it down and led the way, Call and Tamara just behind him.

The path sloped downward, becoming a ledge over a deep pit. Call’s heart started to thud. He knew that large elementals were imprisoned here, knew that theoretically mages were able to approach them without getting eaten — that was the whole point of the imprisonment. But by the dim light of Aaron’s torch, Call couldn’t help feeling a little bit like they were approaching a dragon’s den instead of a holding cell.

A little farther and an alcove dipped into the wall. When they passed it, they saw a winged serpent hovering inside. It was covered in feathers of orange and scarlet and blue, vivid even in the gloom.

“What’s that?” Call asked Tamara.

She shook her head. “I’ve never seen one before. Looks like an air elemental.”

“Should we wake it up?” Aaron whispered.

There must be restraints, Call reasoned, but he didn’t see any. No prison bars, no anything. Just them and a deadly elemental, a few feet away.

“I don’t know,” he whispered back. He racked his brain, thinking over monsters in books he’d read, but he couldn’t think of what this was called.

One of its eyes opened, its pupil large and black, the iris around it a bright purple and star-shaped.

“Children,” it whispered. “I like children.”

The “for breakfast” went unsaid, but seemed clear to Call.

“I am called Chalcon. Have you come to command me?” The eagerness with which it asked the question made Call very nervous. He wanted to command it. He wanted to force it to tell him everything it knew — or, even better, find and devour the spy. But he wasn’t sure what the price might be. If he’d learned one thing during his time in the Magisterium, it was that magical creatures were even less trustworthy than mages.

“I’m Aaron,” Aaron said. Trust Aaron to introduce himself politely to a floating serpent. “This is Tamara and Call.”

“Aaron,” Tamara said, between her teeth.

“We’re here to question you,” Aaron went on.

“Question Chalcon?” the serpent echoed. Call wondered if it was very bright. It was definitely big. In fact, he had a feeling it was bigger than it had been a few seconds ago.

“Someone broke in here a little while ago and freed one of you,” said Aaron. “Do you have any idea who it was?”

“Freed,” Chalcon echoed wistfully. “It would be nice to be freed.” He swelled a bit more. Call exchanged an anxious glance with Tamara. Chalcon was definitely getting bigger. Aaron, standing in front of it with his torch raised, seemed very small. “If you free Chalcon, he will tell you everything he knows.”

Aaron raised an eyebrow. Tamara shook her head. “No way,” she said.

There was a loud thump. Chalcon had flown at them suddenly, his star-shaped eyes burning red with anger. Aaron jumped back, but the serpent was thrashing against an invisible barrier, as if a sheet of glass separated them.

“This guy’s not going to tell us anything,” Call said, edging sideways. “Let’s try to find a different elemental. Someone more cooperative.”

Chalcon growled as they moved away from his cell — it was a cell, wasn’t it, Call thought, even if it didn’t have a door or bars? He kind of felt bad for the winged creature, meant to fly but stuck down here instead.

Of course if Chalcon actually flew around, he would probably pick Call off and snack on him like a hawk nabbing a tasty field mouse.

They moved downward and into a bigger space — a massive hall lined with alcoves, each imprisoning a different elemental. Creatures squeaked and flapped. “Air elementals,” said Tamara. “They’re all air elementals — the other four archways must have led to the other elements.”