The only part that bothered me was that I’d never yet seen an actual demon. And I was getting impatient to try out my new fighting skills on real, live nasties instead of paper targets and straw-stuffed bags. What I really wanted was to use a broadsword like Mab’s, the one she called the sword of Saint Michael, the kind that bursts into flame in the presence of a demon. But instead of a heavy sword with a gleaming bronze blade, Mab started me off with two pieces of wood nailed into a cross shape. Feeling like a kid playing pirates, I protested.

Mab tsked at me in her no-nonsense way, and I knew it was hopeless. It was always the same with Mab: first, technique, then practice—she was big on practice. Next summer, maybe, we’d hunt some demons together. “Small ones,” she said, her voice stern but her accent lilting. “ ’Tis always wise to start small, child.” And so I practiced with a Peter Pan sword.

The next summer, I was eighteen years old, a high school graduate, and feeling more than ready to graduate from Mab’s training program, as well. I was all grown up now, and this would be the summer I finally got to kick some demon ass. When my father decided to spend a couple of weeks in Wales with me, I was eager to show him how impressive my skills had become, to make him and Aunt Mab both proud.

But the day after we arrived, right after breakfast, Mab tossed me the goofy wooden sword. I caught it, surprised, wincing as a splinter slid into my palm. “Broadsword practice in ten minutes,” she announced. “Undoubtedly you’ve forgotten everything I taught you.”

Mab always began the summer with a comment like that, but in front of Dad, it stung. And it was almost like a curse. At practice that day, and the next several days, I was slow, I was clumsy, and I felt like I should be using a stupid wooden sword. Dad standing there watching, saying relax, don’t try so hard, just made it worse. From the look in Mab’s eyes, I just knew that she wouldn’t be taking me demon hunting this summer. Not even for the small ones.

Well, why should I wait for her? I’d trained for six years. I was tired of endless drills and exercises. I wanted to kill a demon. And I thought I knew where to find one.

On the night of July 8—a date burned into my memory—I snuck into Mab’s library and got down the book, the one bound in human skin. My fingers tingled when I touched the spine, and I had a clear vision of a corpse lying on a table and a vat of something bubbling nearby, as a hooded, black-robed figure approached with a curved knife. As the knife made its first cut, the corpse moaned and bright red blood welled from the wound. It wasn’t a corpse at all; someone had been skinned alive to make this book.

I gasped and shoved the book back on the shelf. The vision faded. My pulse hammered through my veins; pain seared the fingers that had touched the book. This was crazy. I wasn’t going to mess with some book that gave you waking nightmares just from touching it. I headed toward the door.

But something made me turn around.

Hundreds of times since that night, I’ve relived that moment, trying to figure out why the hell I couldn’t just walk out of that library and go to bed. Did a spirit call to me? Did some entity possess my body long enough to turn me back toward that book? Or was it just my own stubbornness? I’ll never know.

But turn around I did. I strode back to the bookcase like a woman on a mission and yanked the book from its shelf. This time, there were no visions, no odd sensations. I laughed. It was just a book. I carried the volume over to the window where the moonlight streamed in so that I could read without turning on a light. Flipping through the pages, I glanced at the illustrations until I found the one I was looking for. A demon. A real one.

The thing was hideous. Its skin was deep blue, and flames shot from its eyes. Its mouth bristled with teeth too long and sharp for lips to hide. It hunched over like an ape, its hands on the ground; its fingers and toes ended in nails that looked like daggers. I stared at the picture, fascinated by my own repulsion. This was the kind of thing I wanted to fight.

The words under the picture belonged to a language I didn’t know. Not Welsh—too many vowels. Definitely not English or French. Latin, maybe. Dad would know, but I didn’t dare ask him, because then he’d know I’d been looking at the forbidden book.

Almost idly, I sounded out the words. I don’t think I pronounced them anywhere near correctly. As I spoke, I visualized myself fighting this demon, wielding my flaming sword like Saint Michael himself. The blade whirled and flashed, rending the air with blinding speed. I visualized—I can admit it now, although I couldn’t for years—my father there, cheering me on, as I sliced the demon into little bits of barbecued ghoul.

One thing I’m sure of: I stopped speaking the words before I got to the last one. The book still scared me enough that I wasn’t going to read an entire spell from it out loud. Even though I’d gone to the library determined to conjure a demon so I could kick its ass, the power of that book had shown me I was still out of my league. I’d rebelled against my aunt by taking down the book. That was enough.

I put the book back in its place, making sure its spine was exactly even with the others. A cloud covered the moon, and the room felt dark and cold. I shivered, eager to get back to bed. I tried to hurry across the Persian rug, but my body wouldn’t cooperate. I moved slowly, like I was wading through a river of molasses. My heart pounded with the effort, but I couldn’t make any forward progress. The room felt even colder, and I wondered if I was coming down with something.

Too tired to take another step, I sat down in the middle of the floor. I’ll just close my eyes for a minute,I thought. But I was shivering too violently to sleep. Goose bumps rose on my limbs, on the back of my neck. My teeth chattered so hard they made my head hurt. What was wrong with me?

I heard a bang, like a door slamming, somewhere deep in the house. Great, I thought, Aunt Mab. I’ll really catch it now.

Another bang, closer, then another. The banging grew rhythmic, a steady hammering. What was that? Why would Aunt Mab call in carpenters in the middle of the night? But the next noise wasn’t from a carpenter—it was a horrible, skull-splitting screech, somewhere between a howl and a scream, a sound of pain and rage and something else. The screech came again, and I knew what the something else was—pure, unremitting evil. Fear shot through me like a hundred arrows. I tried to get up, but my legs buckled, unable hold my weight. I stayed there in a heap on the floor, as whatever was making that noise screamed again. Right outside the library door.

I was crying, but I didn’t even have strength to wipe the tears from my face. “Please, God,” I said. “Please, please . . .” I couldn’t think of anything else to say. Every prayer I’d ever learned had evaporated from my mind. All I could do was beg.

The door exploded, leaping from its hinges and shattering into splinters. A hot wind roared through the room, stinking of sulfur and rotted meat. The wind toppled the leather chairs, cycloned papers off Aunt Mab’s desk, hurled the desk itself into the far wall. It didn’t budge me, though. I squinted into the doorway and could distinguish, barely, a massive blue shape.

This demon made the one in the book look like a cartoon. It must have been twelve feet tall, because its head brushed the library ceiling. Jets of blue and yellow flames shot from its eyes. It snarled and snapped, showing hundreds of sharp, daggerlike teeth. It moved its head blindly back and forth, then locked on me, sitting there helpless on the floor. It screeched again, striking at the air with its ten-inch claws, and started toward me.

I screamed. The demon laughed and came closer.

Another step and the flames touched my arm. The pain was indescribable. Heat scorched me from the inside. Flames leaped across my skin, not singeing a hair. But inside my flesh was on fire, my blood literally boiling. I closed my eyes, the world nothing but an inferno of heat and pain and fear and screaming.

And then it stopped.

I looked up. My father stood in the doorway, brandishing Aunt Mab’s sword. The demon had turned to him. As soon as its eyes were off me, the burning stopped. But when it looked at my father, the sword burst into flame.

My father said some words I didn’t understand. Then he said, in English, “Difethwr, I banish thee back to the Hell whence thou came.”

The demon paused. It even staggered—I’m sure it staggered back a little. My father’s power weakened it. I wanted to laugh with triumph. My father would kill this hideous demon, and then he’d teach me how to use the sword. Together we’d become the invincible scourge of the demonic world.

The demon roared, and its eyes shot flames at my father. Dad raised the sword in a defensive posture, using both hands to hold it horizontal, deflecting the jets of flame. He stepped forward with great effort, as though he were pushing back a brick wall. I closed my eyes to utter a prayer of thanksgiving.

And then I heard the sound that has haunted my dreams for ten years. A quiet sound, not like the demon’s din. Half-gasp, half-moan, it came from my father. I opened my eyes to see him on his knees. The sword, its flame extinguished, slanted loosely in his hand, its tip resting on the floor. He was engulfed in a sphere of fire. Although the flame didn’t appear to hurt him—his hair didn’t burn, his skin didn’t blacken—I knew what it was doing to him on the inside.

He groaned and fell forward. The flames followed him, flattening and lengthening to encase his prone body. I screamed and crawled forward to help him, but I was afraid of those flames. I couldn’t force myself to go near them.

My father writhed, and now his screams mingled with my own. The demon was killing him, and I was too paralyzed with fear to do anything.

The flames that consumed my father’s body began to subside, until all that was left was a greenish flickering over his skin. He lay still. Desperate, I searched for some sign that he was okay—a twitching finger or a fluttering eyelid, the slightest rise or fall of his chest—but there was nothing. Nothing at all.

“Dad?” I stretched my hand toward him. “Daddy . . . ?” The burn on my arm hit me with fresh pain, worse than before. I screamed and crumpled in agony. Demonic laughter rumbled through the room. From my curled-up position, I watched twin jets of flame sweep across the carpet. Toward me. I closed my eyes and waited for their excruciating touch.