When I said nothing, he smiled and beckoned to me. Several of the fireflies danced close to him now, tugging affectionately at his hair and kissing his cheeks. He brushed them away and they scattered, only to return to hover around him.

“You are the Mozart girl,” he answered. “Maria Anna.”

“Yes,” I whispered back. “But I’m called Nannerl, for short.”

“Little Nannerl,” he said, his grin tilting playfully up at one side. “Of course.” The way he said my name sent a shiver down my spine. He turned to look at the clavier, and the gesture set the jewels in his hair clinking. “The girl with the glass pendant. I heard your wish.”

How could he have heard something I only held in my heart? A wave of fear rose in me that he might say it aloud. “You were the one in my dream,” I replied.

“Was it your dream, Nannerl?” His fanged smile gleamed in the darkness. “Or are you in mine?”

The lights hovering about his face twinkled. Hyacinth! they cried at him with their tiny bell voices, and he cocked his head at their calls. “Go back to bed,” he said. “We will talk again soon.”

Then, he reached out to the clavier’s music stand, grabbed my notebook, and tucked it under his arm.

Woferl cried out before I did, his baby hands stretching out toward the boy. “He’s stealing your notebook!”

The boy shot me one last glance. “There is a trinket shop at the end of the Getreidegasse,” he said. “Come tomorrow, and I will return your music to you.” He didn’t wait for me to reply. Instead, he turned his back to us and threw himself at the window. My cry choked in my throat.

The glass shattered and the boy blended in with a thousand glittering shards that spilled from the frame. His figure vanished as he fell to the street below. Woferl and I both darted to the windowsill. There, the scene made me step back in shock.

The Getreidegasse, its shops and carriages and silent iron posts, had disappeared. In its place lay a forest thick with upside-down trees, their roots reaching up to the stars, their leaves spreading out on the ground like velvet pools. Twin moons washed the scene into ivory and blue. A faint hum lingered on the night breeze, that same perfect, enticing melody from my dream, whispering for us to come closer. A trodden path wound its way from our building far into the forest’s belly, deep into somewhere we could no longer see, where it faded away into the darkness.

A crooked wooden signpost stood right at the forest’s entrance, pointing to the path. I squinted to read what it said, but couldn’t make out the letters.

The music hanging in the air made my hands tremble, and a sudden urge surged in me. I tugged on Woferl’s hand. “Let’s follow him!” I whispered.

Woferl obeyed without hesitation. Our feet took flight. I unlocked our flat’s front door, swung it open, and hurried out with my brother. My nightgown hugged my thighs as I ran, and the winter floors numbed my bare feet. I ran down the stairs and past the archways, down the third and second stories, down, down, all the way down until I stumbled to a halt at the arched entrance leading to the main street.

I blinked.

The forest, the moons, the upside-down trees, the trodden path, the sign. The music. They were gone. The Getreidegasse had returned to normal, the bakery and winery and the pubs, their wrought-iron signs dangling quietly over their doors, shutters closed and flags pointed up toward the sky. In the distance loomed the familiar, black silhouette of Hohensalzburg Fortress, below which curved the silver ribbon of the Salzach River. I simply stood there, trembling from the cold, clutching the edge of my gown, starving to hear more of the melody from that other world.

Woferl came panting behind me. I caught him right as he ran toward the street, and pressed him close to my side. He looked as surprised as I did.

“Where did he go?” he asked. His breath rose in cloudy wisps.

A sick feeling crept into my stomach. I did not look forward to seeing Papa’s face when he found out that the notebook had gone missing. He would think I’d lost it and shake his head in disappointment. Beside me, my brother noticed my crestfallen expression and sobered immediately, slumping his shoulders and lowering his eyes.

“Woferl. Nannerl!”

The familiar voice startled me. Both of us whirled around in unison. It was Mama, her hair tucked underneath a nightcap, racing down the steps toward us. Her hands clutched at her coat. The image of our mother looked so real, the lines of her face so defined in contrast to the halo of light that had surrounded the boy. Suddenly, I felt how solid the ground was beneath my feet, how biting the chill was in the air. She frowned at me. I am afraid of the cold, Mama had told me before, and I turned my eyes down in shame for forcing her out here on an autumn night.

“Nannerl, what in the world are you both doing down here?” She shivered, her breath rising in a cloud. “Have you lost your senses?”

I started to explain what we had seen. But when I pointed up to where our windows were, where the boy had thrown himself down to the streets—I saw that the glass panes had returned to their normal state. Nothing was broken.

My words died on my lips. Even Woferl stayed quiet.

“I’m sorry, Mama,” I finally said. “We were dreaming.”

Our mother looked from me to my brother, then back again. The hint of a smile danced on her lips before it disappeared again behind her frown. There was a question in her eyes, something curious beyond her stern gaze that wondered what could really have brought us out here.

After a pause, Mama shook her head and held out a hand to each of us. We took them, and she began to lead us back up the stairs. “The very idea,” she murmured, frowning at how cold our hands felt in her warm ones. “I’d not thought you capable of such mischief, Nannerl. Rushing out here with your brother in the darkest hour of night. And in this cold! Thank goodness your father sleeps so heavily, otherwise he’d never let you hear the end of this.”

I looked up at her. “Didn’t you hear the crash in the music room, Mama?” I asked.

Our mother raised a slender eyebrow. “Nothing of the sort.”

I fell silent again. As we stepped back inside our building, I saw the trinket shop at the end of the Getreidegasse from the corner of my eye. The boy’s final words lingered. I wondered what would happen if I met him there.

When I looked at Woferl, he looked ready to say something to Mama—but after a while, his mouth relaxed into a line and he turned his face down. The matter was dropped.

THE PRINCELING IN THE GROTTO

Papa discovered that my notebook was missing the next morning.

He did not shout when he became upset. Instead, his voice would turn quiet like a storm on the horizon, so soft that I’d have to strain to hear what he was saying.