Chapter 1: Lonely Inn in the Rainy Night

The rain intensified in the evening, hammering against the old glass panels of the museum’s dome like nails being flung from above. Otto Wolff sat alone in the curation room. Before him lay the Gelsenbecken stone disc, suspended beneath its acid-proof glass case. Its surface was a dull gray-green, the carvings etched in patterns resembling a dried riverbed. He switched off the main ceiling light, leaving only a single work lamp angled toward the exhibit. The beam sketched across the stone’s face, and the shadows cast by the grooves seemed to shift and breathe subtly. He had been staring at it like this for three consecutive nights, yet the feeling remained: the disc had something to say.

Outside, the rain grew heavier with each passing moment, the wind whipping the droplets against the glass until they rattled with a fine, incessant hiss. Otto didn’t rise to close the window; his gaze never left the disc. For three days now, he had sat here after closing hours, like one stone gazing at another. His colleagues had long since grown accustomed to his eccentricity, though the janitor occasionally paused to glance at him as he passed by.

The disc had been excavated from a Neolithic site along the upper Rhine. Carbon dating had yielded an unusually precise margin of error, prompting the museum to host a special exhibition. Yet Otto felt something was off. He donned his white cotton gloves and let the pads of his fingers trace the rim. The stone was ice-cold, the carvings feeling almost like braille beneath his touch. About seven inches along the edge, he stopped. There was a tiny depression there, crescent-shaped, meticulously polished. Its smoothness clashed starkly with the rough texture of the rest of the stone.

He fetched a flashlight and angled the beam into the groove. No carvings inside, no traces of paint, but the surrounding lines had abruptly changed direction before reaching the depression, as if a string of letters had been brutally cut off mid-sentence. Otto’s breathing slowed. “This isn’t wear,” he murmured. “Someone deliberately polished it away. Something was once set into this spot, and deeply at that—not a later decorative patch.”

He straightened up and rubbed his aching eyes. The sound of the rain flooded the room, and suddenly the curation space felt quieter than usual, so quiet he could hear his own heartbeat. He walked to the window and looked out into the inner courtyard. Under the rain’s veil, the streetlight had blurred into a single smear of yellow; not a soul was in sight. He returned to his desk and sat down again.

He pored over the archaeological log. The excavation record stated: “Stone disc intact, no missing components,” accompanied by a black-and-white photograph from the dig site. He zoomed in on the digital scan. The same depression was visible on the disc’s edge in the photo, but the lighting was too dim for anyone to have noticed it then. Otto took a pencil and traced the outline of the groove on a sheet of paper. By the third attempt, his pen tip hesitated. The shape looked like the edge of a socket for a component.

He set the pencil down and stared at the outline on the paper for a long time. Socket. The word kept circling in his mind. If the disc had originally been an assembly, where had the missing part gone? Why was there no mention of it in the excavation record? He flipped to the last page of the log and found that the initial record had been compiled by the assistant researcher at the time, while the final review signature belonged to Ernst Schwartz.

Otto furrowed his brow. Schwartz was now the head of the archives, having spent over forty years at the museum. He dialed Friedrich Weber’s number. Weber was in Berlin, researching contemporary Germanic runes, and was a leading authority in the field. The phone rang several times before it was picked up; the clatter of cutlery could be heard in the background. “Otto,” Friedrich said, “this isn’t museum opening hours. Are you talking to the rocks again? I remember the last time you called me in the middle of the night, it was over a broken pottery shard.”

Otto said, “There’s a polished groove on the edge of the Gelsenbecken disc. The carvings are interrupted there. I suspect the disc was originally part of an assembly, and that the other half was intentionally removed.”

Friedrich was silent for a moment, then said, “Interesting. But have you run any physical tests on it? Don’t take visual inspection as a conclusion. I’ve seen too many so-called ‘assemblies’ in Bonn that turned out to be fakes held together with glue—some even managed to fool carbon dating.”

Otto replied, “There’s no glue residue or sealant on the groove’s edges. The polished surface is very uniform, as if scrubbed repeatedly with fine sandpaper. If it were a fake, the forger wouldn’t have bothered with such detailed aging; they would have just glued it on.”

Friedrich said, “Send me the photos. I’m heading to Heidelberg next Wednesday for a lecture. I’ll look at it in person then, and I’ll bring a portable spectrometer with me.”

Otto said, “Good. I’ll wait for you. I won’t touch it in the meantime.”

Friedrich said, “Don’t touch it yourself. Some things look like academic questions, but touching them makes it something else entirely. If someone has tampered with it over there, it implies things behind the scenes are not simple.”

Otto hung up and examined the disc again. He felt that the arcs inside the groove were not merely decorative. Their spacing was irregular, their depth inconsistent, as if they were some kind of record. Yet he couldn’t confirm it at the moment. He picked up his pencil and tried to convert the arcs’ spacing into proportional units, only to find that they weren’t uniform but followed a rhythmic pattern of varying density. It looked like a form of counting. He jotted down the numbers, then thought it might be a stretch, and pushed the paper aside.

He got up to fetch old surveying maps from the archive room. As he passed through the corridor, he noticed a janitor pushing a cleaning cart, wiping down a display case in the corner of the exhibition hall. Otto nodded, and the janitor returned the smile before continuing their work, head down. Otto didn’t think much of it and walked into the archive room.

The archive room was bathed in the dim, yellow glow of the overhead lights. He rummaged through the metal cabinets until he found the survey map buried beneath a thick stack of old reports. When he pulled it out, a layer of fine dust puffed off the paper. He unfolded the map and realized there was no groove marked along the edge of the stone disc. Frowning, he checked the signature of the surveyor in the bottom right corner: Ernst Schwartz, the director of the archives. The date on the drawing was 1974, nearly thirty years before the artifact’s excavation.

Otto murmured, “A map surveyed in 1974? How could it predate the discovery? This isn’t the original. It’s either a copy or it depicts something else entirely.”

He held the document up to the light. The paper had yellowed with age, and small holes from insect damage pocked the edges; it certainly looked old. But if the stone disc hadn’t been unearthed until 2003, how could a survey exist? Unless the map wasn’t of this disc, but of another object. Or, perhaps, this specific disc had been discovered by someone long before 2003, though its existence remained unpublicized.

Otto took the map back to the curation room, passing the janitor again. This time, he noticed the janitor’s cleaning cart was parked in an unusual spot—a blind spot for the security cameras. Otto kept his expression neutral as he returned inside and spread the map out to compare it with the stone disc. The patterns on the map matched the disc’s engravings almost perfectly, but the map included an extra ring of fine graduation lines along the edge, annotated with a series of pencil markings that looked like coordinates.

Otto copied the numbers onto a separate sheet of paper, then studied the graduation lines on the map. They were evenly distributed along the rim, resembling some kind of measurement marker. Suddenly, he remembered the irregular arcs etched on the inside of the groove. He cross-referenced them with the map and found that the positions of the graduation lines aligned exactly with the arcs on the stone disc. He drew a sharp breath. This wasn’t just a survey map; it was a record map. It documented the precise location of the arcs on the disc.

A faint metallic scraping sound came from outside the door. Otto looked up. The janitor stood in the doorway, holding a spray bottle and aiming it toward the stone disc. Otto frowned. “Which cleaning service are you with? It’s not cleaning hour, and the side entrance to the exhibition hall is locked. How did you get in here?”

The janitor didn’t answer. He took two steps forward, unscrewed the cap of the spray bottle, and released a pungent, stinging odor. Otto instantly recognized the smell of strong acid. He shot to his feet and stepped in front of the disc. “Put it down. Leave the bottle where it is. This is a national cultural relic. If you touch it, you’ll face serious criminal charges.”

The janitor glanced at him with a calm, almost businesslike expression, as if performing a routine task. Otto quickly scanned the room. The alarm bell was at the end of the corridor, out of reach. He stepped back, letting the pool of light from the work lamp wash over the intruder’s face. In that harsh light, he noticed a dark cuff peeking out from under the man’s sleeve—certainly not part of a standard janitor’s uniform.

Otto said, “You’re not a janitor. You’ve been casing this place all day. You’re after this stone, aren’t you?”

The janitor gave a slight smile and aimed the nozzle of the spray bottle at the disc. Otto didn’t scream. Instead, he grabbed the flashlight from the desk and aimed the beam directly at the acid bottle. The man flinched instinctively, turning his head away. In that split second, Otto slammed his emergency switch under the workbench with his other hand. The side door to the exhibition hall clicked open. It led to the inner courtyard.

The janitor glanced at the open door, then back at Otto, seemingly assessing the distance. He didn’t chase after Otto. Instead, he turned and walked to the workbench, pulled an old key from his pocket, and drove it forcefully into the wooden surface. The sound of metal striking wood rang out sharply.

He backed toward the window, vaulted the sill, and vanished into the curtain of rain.

Otto froze for a few seconds, then walked over to the workbench to examine the key. It was made of brass, and the handle was cast with an eagle emblem. Beneath the eagle’s talons was a circular wreath. Otto had seen this style before; it was the seal design of a specific institution from the old era. He picked up the key and turned it over. Three numbers were engraved on the back, identical to the coordinates marked on the archival map.

Otto stared at the key, the sound of the rain filling the entire room. He said in a low voice, “A map from 1974, hidden grooves, and this key... this stone isn't just an ordinary artifact. It was hidden by someone for decades.”

He gripped the key in his palm, the cold brass seeping into his skin. He realized that since the janitor had managed to bring in strong acid, he must have had complete knowledge of the museum’s security cameras and patrol schedules. When had he first started watching this stone disc? Was it after the opening of the special exhibit, or even earlier? Otto walked to the window. The rain was so heavy that no figures could be seen in the deluge. Streetlights swayed in the wind and rain, their light flickering on and off.

He dialed Anna Wagner’s number. Anna was a research assistant at the museum who lived in the old town district. The phone rang twice before she answered. “Otto? It’s so late. Is something wrong at the museum? You sound off.”

Otto said, “Someone tried to etch the Gelsenbecken stone disc with strong acid. The man got away, leaving behind an old key with an eagle emblem. It has three numbers engraved on it.”

Anna was silent for a moment, then said, “Did you call the police? You can’t let this wait. What if he comes back?”

Otto replied, “Not yet. The three numbers on the back of the key match the coordinates on a 1974 map in the archives. The map was signed by Director Schwartz, and the date is nearly thirty years before the excavation.”

Anna said, “Then the dating doesn’t add up. The excavation was in 2003; a survey couldn’t have existed in 1974. Unless that map was a copy, or was drawn well before the discovery—which would mean someone already knew where this stone was located long ago.”

Otto said, "Right. This stone might not have been discovered for the first time in 2003. Someone may have encountered it before."

Anna said, "Call the police first. Don't investigate on your own. The eagle emblem on the key is the seal of an official institution from the old regime. That thing involves more than you can handle alone."

Otto looked at the key on the workbench and said, "I will call the police. But I want to speak with Curator Schwartz first. He signed that blueprint, so he must know something."

Anna said, "Keep the key safe and don't let anyone else touch it. I will be at the archives early tomorrow morning to wait for you. I'll accompany you when we press for answers."

Otto said, "Okay. See you tomorrow."

Anna said, "Otto, don't stay at the museum tonight. Since that person dared to come once, they might come a second time. You can't hold the line alone."

Otto hung up the phone. The rain was still falling. He placed the key in his pocket.