Chapter 1 — Room 404 Sea View

Nhi used a laser ruler to scan the east wall of the Hai Dang Hotel. The screen showed a length of 8.2 meters, but the construction drawing she held in her hand said 10.6 meters.

She measured again. The gap is enough for a small room. She moved the probe to the corner of the wall, pressed it a third time, and wrote the number into the spreadsheet on the tablet. Three measurements, three almost identical results: 8.19 — 8.21 — 8.20. The error is within the allowable amplitude of the device. The drawing is what's wrong, not the wall.

“This drawing is old,” Vu said from behind. He was checking the bearing column, his hands covered in mortar dust, a technical notebook tucked under his armpit.

“How old is it?”

“The original year the hotel opened. Forty years.” Vu tapped his finger on the concrete pillar. "But the main structural data still matches the current state. Only this part of the wall is askew."

Nhi turned to the fourth floor plan page. Room 403, hallway, emergency stairs. At the edge of the drawing, a blurred rectangle appears and is then crossed out with a faded pencil line. Next to it is written 404, in small handwriting, tilted to the left as if written hastily.

The hotel has 403 rooms. Bidding documents must be clearly stated, notarized, and kept in three different places. Nhi checked before accepting the job, comparing each number with the list of assets attached to the contract. There is no room 404 in any official documents.

Mrs. Hanh, the hotel owner, wanted her to complete the restoration documents in two months. She does not like discrepancies that cause banks to delay disbursement. At the first meeting, she said directly: "Miss Nhi, I need a clean set of documents, nothing that would cause the appraiser to ask any more questions."

Nhi took photos of the wall with a specialized camera, numbered the photos according to standard storage procedures, then asked to open the fourth floor warehouse for direct comparison. Mr. Tu, the old maintenance worker, led her to the end of the hallway and said that the warehouse door had been welded since the landslide eighteen years ago.

“Are there any rooms there?” Nhi asked, placing her hand on the peeling paint around the door frame.

Mr. Tu looked at her but did not answer immediately. He stood still for a moment, his eyes stopped at the number 404 on the drawing she was holding, then spoke, his voice hoarse because of age or something else she could not yet guess. “You asked the wrong person.” He only gave a bunch of keys, one of which was unnumbered and had tarnished metal.

“Which door does this one open?”

"I don't remember anymore. I've kept it since I worked here, I can't bear to throw it away."

Vu measured the distance from room 403 to the warehouse wall with a tape measure, comparing it with the original structural drawing he brought with him. There are no columns or beams suitable for a closed room in that location. Technically, that space can only be an alcove or a blocked passage.

Nhi took notes in the construction site book, writing regularly according to professional habits: "Room 404 exists on paper, not on the structure. Need to compare the maintenance logbook and original bidding documents before concluding that it is a drawing error."

She brought the computer to the temporary table set up in the lobby, opened the digitized drawing file to correct the incorrect wall section, replacing 10.6 meters with the actual measured number. The rectangle disappears from the visible layer. She saved the new file, closed the software, and restarted the computer following the system error checking procedure.

When reopened, room 404 appeared on the opposite side of the hallway, looking straight out to the ocean. Not the same location. Another location, away from the place about four meters old, close to the window at the end of the floor.

Nhi re-reads the file's edit history. There is no record of any operation that created a new rectangle. She checked the name of the last user who saved the file — it was her account, three minutes ago, right when she saved the edit.

She didn't tell anyone. She printed the drawing, folded it in the same way and placed it in a moisture-proof bag with other important documents of the project. Outside the window, the sea lay below the cliff, so blue that it was not the same color as in her memories—memories that she had never truly trusted, since the day her mother failed to return from those waters eighteen years ago.

In the afternoon, she returned to her temporary office, a small living room on the ground floor converted into a construction site office. The desk is close to the window, opposite is a pin board filled with floor plans, photos of the current situation, and a two-month progress calendar covered in red letters.

She reopened the original bidding document and found the appendix recording the number of rooms on each floor. Fourth floor: fifteen rooms, numbered 390 to 403 in L-shaped hallway sequence. There are no gaps in the numbering sequence. There is no room for a sixteenth room.

She called the old construction records company, which kept microfilm copies of all the hotel's licensing documents from the early years. The staff on the phone said it would take three working days to look up, because the archive was in the category of construction documents before being fully digitized.

“What specifically do you need to look up?” asked the other.

“Any drawings that mention room 404, or code 404 in any form,” Nhi replied, reading slowly so the recorder wouldn't make a spelling mistake. “Including drawings that have been removed from official records.”

She hung up the phone and sat looking out the window for a while. Outside, the work crew was cleaning up the broken bricks in the front yard, the sound of the drilling machine mixed with the sound of waves echoing from the foot of the cliff. The Hai Dang Hotel stood silently behind her, eighteen years of closure leaving a thick layer of dust on every surface that had not been cleaned.

Vu stopped by before the hour ended and placed another printout of the fourth floor plan on the table, this time from a set of construction insurance documents she had never seen before. “Found this in the manager's old filing cabinet,” he said. “I don't know if it's related, but it's worth taking a look before concluding this is just a software error.”

Nhi opened the paper. In the lower corner, a faded stamp bore the date of the year of the landslide, and next to the familiar room numbers, a handwritten note with half of it crossed out: “...404-B — transfer…” The rest was illegible because water stains had eaten away the paper.

“This is not a software error,” she said, her voice slowing. “This is something someone tried to erase, but didn't erase it all.”

Vu sat down next to the table, picked up the paper and looked at it under the table lamp. “404-B,” he read again. "The letter B may be a symbol for an auxiliary area in old technical documents. I have seen similar coding in some coastal projects - the main area has regular numbers, the secondary areas have letters."

“What is the annex for?”

"Many things. Warehouse, computer room, technical area are not for guests." He put the paper down. “But if it is an annex, why does the new drawing show it as a room overlooking the ocean, exactly where a living room should be?”

Nhi has no answer. She opened the digitized drawing again, zooming in on the corner where the rectangle had just appeared. Its outline is regular and has reasonable proportions compared to the Another room, unlike a random software display error. It is drawn like a real room, with full size annotations on both sides.

“I'll contact the software writer,” she said. “Ask if there are any hidden data layers that are not shown by default.”

“And I will ask Mr. Tu again,” Vu replied. "He's been working here since before the landslide. If anyone remembers what code 404-B means, it's him."

They divided the work, each going their own direction, in the familiar way of working on a survey project — not speculating before they had enough data, not ruling out any possibility just because it sounded unusual.

Before leaving the construction site office, Nhi reopened the folder of photos taken on the east wall that morning, reviewing each photo in chronological order. In the last photo, in the lower right corner, there was a small blur on the reflective window glass — too faint to tell, but enough that she saved that photo separately in a new folder, naming it “needs to be checked again.”

She turned off the computer, locked the door to the construction site office in accordance with the end-of-day security procedures agreed upon with the management board, then walked slowly to the parking lot. The sea breeze blew stronger than in the morning, bringing cold salt breath to my face. She glanced back at the entire building one last time before getting in the car, the yellow construction site lights illuminating the fourth floor facade, where dark windows lined up in a regular row—except for a small gap between room 403 and the wall at the end of the hallway, where there were absolutely no windows according to the original drawing she had just checked, but the light seemed to reflect something she wasn't sure was glass or just her imagination working overtime after a long day of measuring.