Chapter 1: Rainy Night, Off-Beat

Dresden’s rain fell like a thousand tiny needles, pinpricking the glass dome of the Saechsische Theater until it creaked under the sheer volume.

Anna Wolff stood in the shadows behind the side curtain of the stage, her fingers unconsciously tracing the worn texture of a yellowed paper tape. It was a keepsake her grandfather had shoved into the inner pocket of her coat before he died, but tonight, it felt far hotter than any music performance in the rehearsal hall. The piano practice stopped with an abrupt jolt; the director was impatiently tapping his music stand, shattering her daydream.

“Anna! Is your metronome broken?” the director barked, spittle flying in the dim light. “Rhythm is your bread and butter. Why do you sound like a rusted gramophone today?”

Anna didn’t argue. She just tilted her head slightly, holding the paper tape up to her face. The irregular holes in the tape cast long shadows under the spotlights, looking suspiciously like some ancient sheet music. She closed her eyes. No melody surfaced in her mind. Instead, a cold, logical order took hold.

“Give me three minutes.” Her voice was quiet, but it cut through the chaotic noise of the backstage.

She didn’t touch the upright piano. Instead, she pulled a small recorder out of her pocket. It was one of her grandfather’s old gadgets. The tape inside was worn thin, but the mechanical parts were still intact. Anna stuck the paper tape onto the recorder’s spindle. As the cylinder turned slowly, the holes blocked the light in a rhythmic pattern, triggering the highly sensitive photocell inside.

Click, click, long, short.

At first, the sound was just monotonous mechanical noise. But as Anna closed her eyes and tapped her finger on the paper tape, mimicking the frequency of the rotation, a miracle happened. The seemingly random holes rearranged themselves in the rhythm of her mind. She wasn't listening to sound; she was reading the “intervals.”

Three long, two short, one long, four short.

It wasn’t Morse code. It wasn’t any known musical notation. It was an ancient encoding based on the tidal cycles of the Elbe River, something only someone intimately familiar with Dresden’s underground water system could understand. Anna’s breath quickened. Her fingers danced over the tape, like a pianist running across the black and white keys, each strike landing precisely on a beat that didn’t technically exist.

Suddenly, a faint background noise slipped in from the recorder, like an impurity dredged up from the depths of the tape. It was a child’s voice—clear but trembling—cutting through the electrical hiss. It spoke a string of numbers with terrifying clarity:

“Tomorrow, at 19:00 sharp. Elbe River, 14.2750 North, 12.1160 East. Don’t trust the key. Trust the echo.”

Anna’s eyes snapped open. Her hand hovered in the air, her fingertips turning white from the pressure. She knew that coordinate better than her own heartbeat. It was the entrance to an abandoned air raid shelter under the Elbe Bridge. It was also the location of the “treasure” her grandfather had rambled about his whole life, though he never explicitly named it.

“Are you done?” The director leaned in, impatient, studying the complex look on Anna’s face. “If that’s all your prep, the show is going to be a disaster.”

“I have a call to make.” Anna pocketed the recorder and shoved the tape back into her coat. Her eyes were sharp, like a freshly honed scalpel. “And if the person who’s not showing up tonight doesn’t appear, my prep is over. Forever.”

She burst out of the backstage, swallowed instantly by the curtain of rain. Water dripped from her hair. Standing under the theater’s porch, she dialed Professor Ernst Vogt’s number. The long dial tone was grating against the sound of the storm, but it broke when his voice came through—low, tired, carrying the scent of aged cigars.

“Anna? Calling me at this hour?” Ernst Vogt sounded exhausted. “I’m listening to Bach’s Well-Tempered Clavier. You’d better have a more urgent reason than the rain.”

“Professor Vogt, I need you to verify something,” Anna skipped the pleasantries and got straight to the point. “The files the City Hall destroyed after the 1943 bombing of Dresden. You mentioned one document about a ‘Blue Shield’ project. It involved a map.”

Silence on the other end. The piano in the background seemed to stutter for a second.

“Anna, it’s been only three days since your grandfather died. And you’re already digging up his old skeletons?” Ernst Vogt’s tone turned harsh, like a cold stone wall. “That map is a myth. The German high command deliberately spread false information to coordinate with the Allied bombing. What you have in your hands is probably just a piece of scrap paper.”

“If it’s scrap, then why does that perforated tape generate a tidal code with coordinates precise to four decimal places?” Anna countered, her voice still cool, though her fingers had clenched into fists inside her pocket. “And a child’s voice was mixed into the code. That was a recording of my grandfather when he was a kid. Unless... the map actually exists, and it was split up and hidden.”

The breathing on the phone grew heavier. After a long pause, Ernst Vogt sighed, as if he had finally let go of a stubbornness he’d held onto for half a lifetime.

“That coordinate... it’s a private warehouse in the Old Castle District. The owner is Matthias Weber, an appraiser of ancient books. He stopped all activity two months ago.”

“Did he die?”

“The police found a body on the banks of the Elbe River three days ago. Identity unconfirmed. I just checked the news, and it looks like...” Ernst stopped. “Anna, listen to me. If you’re going there, bring a weapon. Not a gun. Your brain. That place is now a no-man’s-land. William Frank’s people have sealed off the surrounding three blocks.”

“Frank?” Anna frowned, the image of the municipal archaeology bureau official flashing in her mind—he was always in a crisp new trench coat with a friendly smile. “Why would he care about a dead man’s legacy?”

“Because that map might not be scrap paper.” Ernst Vogt’s voice dropped to a whisper, like they were conspiring. “Frank has been filing applications to excavate the ‘unexploded ordnance clearances’ along the Elbe River. It’s prime real estate. If there are unregistered artifacts at the location marked on the map, he’d have a legal excavation license. He’s not looking for treasure. He’s land-grabbing.”

Anna hung up. The rain washed furrows down her face. She didn’t bother with her car; she walked toward the subway station. On a rainy night like this, the train was the only shortcut.

The car was empty, save for the mechanical female voice of the announcer calling out the stops. Anna leaned against the cold metal wall, eyes closed, replaying the child’s voice.

“Don’t trust the key. Trust the echo.”

Echo. The reflection characteristics of sound in a closed space. The air raid shelter under the Elbe Bridge was a typical reverberation chamber. If the map fragments were hidden there, they must have used the principle of sound refraction to conceal them.

The train rattled into the station. Anna hopped off, merging into the wet streets. She didn’t go straight to the abandoned warehouse by the river. Instead, she turned into the Old Town, passing a dimly lit antique book auction house. The display window held yellowed German texts, the light hanging over them yellow and stale, like moldy cheese.

The owner, Otto Krueger, was behind the counter wiping his goggles. He flashed his signature smooth smile when he saw Anna walk in.

“Miss Wolff. So late in the evening. Trying to find a new home for your grandfather’s collection?” Otto Krueger’s tone was light, like he was selling a high-end pen. “The 'Bavarian Topography' in there is out of print. This is the only copy.”

“Mr. Krueger,” Anna stepped forward, her gaze sweeping past him to a dust-covered map tablecloth in the corner. “I’m not here to buy books. I’m looking for a man. Matthias Weber, ancient book appraiser. Has he been here recently? To repair or trade anything?”

Otto Krueger stopped wiping his goggles. The lenses reflected a strange, cold light.

“Weber? That old academic?” Otto shook his head, taking a half-step back to create distance between them. “He hasn’t been here. But someone claiming to be a ‘family heir’ has dropped by three times recently, asking about the whereabouts of a batch of water-damaged parchment rolls. That person was wearing gloves, and they were very polite, but their eyes... they looked like they were staring at prey.”

“Wearing gloves?” Anna caught on to the detail instantly. “Why not just use their hands?”

“To protect their fingerprints. And their skin,” Otto Krueger shrugged, downplaying it. “Today’s young people even wash their hands before robbing a house. Before he vanished, Weber mentioned an incomplete ancient map to me. It was missing a corner. He said that corner was the ‘eye.’ Without it, the map was just a blind skin.”

Anna’s heart gave a sharp jolt. The missing corner. Among her grandfather’s keepsakes, there was indeed a strangely shaped scrap of paper, its edges charred black, as if torn from something larger.

“When did he see that map last?” Anna pressed.

“Two weeks ago.” Otto Krueger moved behind the counter and pulled a yellowed receipt from a drawer, sliding it across to Anna. “He traded it for a rare Bach manuscript. I didn’t ask for details. After all, in Dresden, some things are more valuable than gold. And more dangerous.”

Anna pinched the receipt, feeling the rough texture of the paper. On the back, a small line of pencil had been written, nearly blurred by sweat: *At the corner, under the river*.

“Thanks, Otto,” Anna said, folding the receipt and shoving it into her wallet. “Save me a first-edition if you find one.”

“Will do, will do.” Otto Krueger watched her disappear into the rain curtain, his smile vanishing instantly, replaced by a deep sense of wariness. He picked up the phone on the desk and dialed another number, his voice dropping to a whisper: “Krueger reporting. Miss Wolff from the Wolff family knows about the map. Any movement on Frank’s side?”

Heavy breathing came through the line. Finally, William Frank’s cold voice answered: “She’s lost in the rain. Let her drown at the bottom of the river.”

Anna stepped out of the auction house. The rain had intensified. She stood at the street corner, staring at the handwriting on the receipt, her mind rapidly mapping out a route. Under the Elbe Bridge. The entrance to the air raid shelter.

By the time she got there, the rain had let up slightly, but the river water was murky, rolling black foam. The door to the abandoned warehouse was tight shut, the smell of rust hanging thick in the air. Anna circled to a ventilation window on the side, peering through the dust-covered glass.

Inside was pitch black, save for the monotone rhythm of rain dripping through the damaged roof. Suddenly, she spotted a pale silhouette in the corner.

She kicked the side door open without hesitation and charged in.

“Move!” Anna barked, though she was unarmed, her presence commanding enough to make anyone flinch.

No one answered. Just the dripping of water.

Anna clicked on her phone flashlight. The beam sliced through the darkness, illuminating an old wooden table in the center of the warehouse. On it lay an unrolled ancient map. The parchment was brittle, its edges torn unnaturally. A man lay slumped beside the table, wearing a raincoat splattered with mud. His hands were clutched tightly around a corner of the map, his knuckles white. Even in his final moment, he was trying to grab that missing puzzle piece.

Anna rushed over, dropped to her knees, and checked his carotid artery.

No pulse.

The dead man’s eyes were wide open, his face frozen in an expression of pure terror. His left hand still gripped a smartphone. The screen flickered from the impact. Anna’s trembling finger lit up the display. The lock screen was blank, as the dead man had clearly set it up with a fingerprint unlock.

But just as she was about to pry open his stiff fingers, the phone screen suddenly lit up. A new email notification popped up.

The sender ID was a string of seemingly random numbers. But Anna recognized the pattern—it was the domain suffix of her grandfather’s old email account.

The email subject line contained only one word: “Echo”.

Anna’s finger froze on the screen. Rainwater leaked from the dead man’s shattered eye socket, dripping onto the missing corner of the map, as if mocking this chase that spanned time and space.