Free The Iron Trial by Holly Black, Cassandra Clare

until you know it well, it’s easy to become lost.”
    Lost in the tunnels , Call thought. It was the exact thing he’d been scared of since he’d first heard of this place. He shivered as he remembered his nightmare about being trapped underground. Some of his doubts were creeping back, his father’s warnings echoing in his head.
    But they’re going to teach me how to fly, he thought, as though arguing with someone who wasn’t there.
    Master Rufus held up one large hand, fingers splayed, and said something under his breath. The metal of his wristband began to glow, as though it had turned white-hot. A moment later, with a loud creaking that sounded almost like a scream, the doors began to open.
    Light poured out from between them, and the kids moved forward, gasping and exclaiming. Call overhead a lot of “Cool!” and “Awesome!”
    A minute later, he had to grudgingly admit it was kind of awesome.
    There was a vast entrance hall, bigger than any inside space Call could have ever imagined. It could have held three basketball courts and still have room left over. The floor was the same glittering mica he’d seen in the illusion back at the airplane hangar, but the walls were covered with flowstone, which made it look like thousands of melting candles had slicked the walls in dripped wax. Stalagmites rose up all along the edges of the room, and huge stalactites hung down, nearly touching one another in places. There was a river, a bright glowing blue like luminous sapphire, cutting through the room, flowing in through an archway in one wall and out through another, a carved rock bridge crossing it. Patterns were cut into the sides of the bridge, patterns Call didn’t recognize yet, but they reminded him of the markings on the dagger his dad had thrown to him.
    Call hung back as all the apprentices from the Trial flooded in around him, forming a knot in the middle of the room. His leg felt stiff from the long bus ride and he knew he would be moving slower than ever. He hoped it wasn’t a long walk to where they were supposed to sleep.
    The huge doors closed behind them with a crash that made Call jump. He spun around just in time to see a row of sharply pointed stalactites, one after another, drop from the roof and thud into the ground, effectively blocking off the doors.
    Drew, behind Call, swallowed audibly. “But — how are we supposed to get back out?”
    “We’re not,” Call said, happy to have an answer for this, at least. “We’re not ever supposed to get out.”
    Drew edged away. Call supposed he couldn’t blame him, though he was getting a little tired of being treated like a freakazoid just for pointing out the obvious.
    A hand took hold of his sleeve. “Come on.” It was Aaron.
    Call turned and saw that Master Rufus and Tamara were already starting to move. Tamara had a swagger in her step that hadn’t been there before, under the watchful eyes of her parents. Muttering under his breath, Call followed the three of them through one of the archways and into the tunnels of the Magisterium.
    Master Rufus held up one hand, and a flame appeared in his palm, flickering like a torch. It reminded Call of the fire resting on the water in the final test. He wondered what he should have done to really fail — to fail in a way that wouldn’t have meant his coming here.
    They walked one by one through a narrow corridor that smelled faintly of sulfur. It spilled into another room, this one with a series of pools, one of which bubbled away muddily and another full of pale, eyeless fish that dispersed at the sound of the humans’ footfalls.
    Call wanted to make a joke about how Chaos-ridden eyeless fish might be undetectable if they were servants of the Enemy of Death, because, well, no eyes, but he managed to creep himself out instead, imagining them spying on all the students.
    Next they came upon a cavern with five doors set into its far wall. The first was made of iron; the second, copper; the third,