Chapter 15 — The Thirteenth Landmark

The observation network of North Shore residents was established in one afternoon. No one calls it a movement, because big words often scare people. They just split up and stood at the sewers, took pictures of the water level with a homemade ruler, wrote the time on paper and sent it to Bich.

Phuc created a spreadsheet, blue for the actual water level, red for the RiverEye number. Every time the difference exceeded ten centimeters, he sent out a warning in the group.

“Look,” Phuc said, pointing to the screen. "Station nine just dropped 18 centimeters, but people on Reed Street reported the water rising."

An inspection. Another optical sensor has been activated in the system. The automatic model continues to downshift.

“They don't need drivers anymore,” she said. “Software is doing the work.”

Khoi put down the rescue bag. “So it must be turned off from the source.”

“The source is in the Operations Center.”

“Can I come in?”

Nam shook his head. “My card is disabled.”

“Which way is there?”

"There's an auxiliary engine room down in the square. The people who created the system used to set aside a maintenance door in case of a power outage."

An looked at him. “I didn't say it from the beginning.”

“I'm afraid you'll use it.”

“I'm afraid people will be flooded.”

“The two fears are not mutually exclusive.”

They went to the square through the drainage tunnel. The maintenance door is covered by a billboard advertising "Tan Giang — life by the water". Phuc used a crowbar to pry off the board, revealing the steel cover.

Below is a slippery staircase with water flowing from the cracks in the wall. Khoi tied the rescue rope around An's waist.

“If you miss, pull three times.”

“What if I fail?”

“I pulled twice.”

The secondary computer room contains dozens of network cabinets. The green light flashed, but one cabinet was opened. The signal wire from RiverEye connected to the new server has the Tan Giang stamp.

An equipment plug of the B-13. The screen shows the command log. There is an automated task named “recovery_event_13”, which started at 4:59 and has no owner.

“They set up a fake event and let the system run on its own,” Nam said.

“Can you delete it?”

“If deleted, all warnings are lost.”

“Do not delete. Separate it from real data.”

An creates an independent channel, transmitting measurements from Marker 13 and the mechanical stations. This requires an admin code. Nam enters the old code, but the system requires confirmation from the last signer.

“The last signer was DQD-01,” An said.

“Where is that code?”

“On the ring?” Phuc asked.

Nam shook his head. “No. DQD-01 is an account, not a code.”

Bich sent a text message: "I have a photo of the ring. On the inside is engraved 1309."

An entry 1309. Open system.

A new screen appears, showing the raw data stream. The real RiverEye and the edited RiverEye are separated into two columns. The edit column has a gray caption: “to serve the recall model”.

“Take a picture,” An said.

Phuc recorded video of each screen. Bich broadcast live from the tunnel, although the signal was weak.

On the stream, residents sent a series of comments. One man wrote: "My house is on Reed Street. No amount of fake data can replace the water in the kitchen."

An turns on the microphone. "We are separating the real data from the model data. If the signal is lost, continue recording the water level manually."

Nam looked at his watch. “Forty minutes left before the next cycle.”

“We need to turn off the task.”

“Can't turn it off from here.”

“So push the record to every station.”

"If pushed, the system will issue a real warning, but will also reveal all confidential data."

An looked at Bich. “Can you save it?”

“If you put it on four servers at the same time.”

“Let's do it.”

Nam hesitated. “If it's wrong, it's successful The city will know every mistake for twelve years. Some people will be prosecuted, but there will also be people who will panic.”

“They need to know before they sign.”

Nam entered the command. Three servers accepted, the fourth refused. Server name: HN-CTRL.

“That's my phone,” Nam said.

“Do you still have the right?”

“Someone used my name.”

An opens the computer log. The most recent orders were sent from Nam's account, but the physical address is at the provincial meeting room. One person in the meeting is in control.

“Trang,” Bich said.

I'm not sure. Duy is also accessible. She pushes the record to the fourth server manually. System response: “RECONFIRM OPERATOR.”

Nam put his hand on the reader. “I confirm.”

“I will receive all orders on the machine myself.”

“I've had enough.”

He pressed. Data spreads.

Immediately, all the screens in the square displayed a yellow water level graph. Public speakers read the actual water level, no longer have corrected numbers. Residents looked at each other, then at the red lines on the door.

At the provincial meeting room, officials panicked. Trang snatched the phone away from an employee.

“Who grants permission?”

Staff did not respond. Bich played back Trang's audio: "Just visible damage."

The recording spread across the internet.

An turned south. “What about the cycle?”

“Blocked by the real system. But the fake mission has gone into emergency mode.”

"Mean?"

“It will open every valve to prove the prediction correct.”

A loud vibration echoed in the engine room. Water poured over the stairs. The gas gauge said it was safe, but the water level increased every minute.

Khoi looked out the door. “We have to go.”

An took the hard drive. “Can't leave the server.”

“The server can be replaced.”

“Data no.”

Phuc shook his head. “Sister, I have finished filming.”

An looked at the video on his phone. Thousands of people saved copies.

Nam turned off the auxiliary circuit breaker. The screen is dark, but the system is broadcasting data out.

“Now go,” he said.

They climbed onto the street. In the distance, three culverts opened simultaneously. Water flows like silver strips under street lights. A building under construction in Tan Giang shook, the glass on the lower floor cracked.

Duy called An again. His voice was no longer calm.

“What did you do?”

“Make your measurements public.”

“You just threw the whole city into chaos.”

“The city has been in chaos since the moment you put the code DQD-01 into the system.”

“If the building collapses, you will be responsible.”

“If the building falls because we saved the North Shore, history will know why.”

Duy was silent. Then he said, “I'll meet you at Milestone 13.”

The call ended.

Khoi looked at An. “Trap?”

"Maybe."

“Then don't go.”

An looked at the water level chart on his phone. A new red spot appeared in the west, where there had never been a measuring station.

“Milestone 13 is not the end point,” she said. “There is a fourteenth mark under the lake.”

And it just sent out a signal.

The Milestone 14 signal is not a simple water level warning. It is a series of pressure pulses sent through an underground pipe, each pulse separated by exactly thirteen seconds. Nam decoded the code in the community computer room and realized that this string contained the coordinates of a bunker under the urban area.

“If the cellar remains, it can absorb large amounts of water,” he said.

“But locked.”

“Locked with the system creator's code.”

An looks at the code HN-CTRL in the log. “Your code.”

“I don't remember creating the key.”

“Maybe someone else is using the account.”

“Or I created it while I was unconscious.”

Nam said that the night before the old flood, he worked continuously continued for more than twenty hours. Duy gave him a model, saying that if he kept the door in neutral, the hospital would be saved. He entered the code, then An's father told him to leave and give the file to Loc.

“I think I'll just lock it temporarily,” Nam said. “After that everyone called me the man who saved the city.”

“You don't fix it?”

"I tried. But the old system lost power. I took a job at the new center to find a way to open it."

An looked at him. “Twelve years to find a lock?”

“Twelve years to find courage.”

Khoi did not comment. He brought a wooden box that belonged to Thao's mother. Inside are evacuation records, photos of vehicles blocking the road and a rescue team badge.

“Thao didn't just record,” Khoi said. "She drew the water line with chalk on the station wall. I found the remaining mark."

Bich projects a photo of a chalk mark. It connects the south culvert with the old lake, then returns to the North Shore. Thao knew the third discharge route before the engineer.

An felt his chest was heavy. Too many people have seen parts of the truth, but no one has the power to piece it together.

“We have to open the vault,” she said.

“No access,” Nam replied.

“There's my father's code.”

“Voice recordings only unlock one layer.”

“Then find the other class.”

They arrived at the old measuring station under the bridge. In the concrete floor there is a mechanical lock box, carved in a semicircle. An opened it and saw another tape and a photo of Mr. Vu standing next to Nam.

His voice on the tape said: "If I can't open it, use someone who witnessed it to open it. Not the signer."

The witness was Nam. He listened to that sentence three times, then put his hand on the lock.

“I confirm,” he said.

Lock does not open.

An looked at the photo. Behind Mr. Vu and Nam, there is a woman standing next to the control panel. The face is covered, but the wrist wears a square watch.

“Trang wasn't the only one there,” Bich said.

Nam recognized the watch. “That's Mrs. Vinh.”

“Le Hoang Vinh's mother?”

“She was the foundation president before her son took over.”

“So N's signature is hers?”

"Maybe."

An turned the photo to the back. Father's handwriting: "The one who gives orders never holds the crank."

Khoi asked: "What do we do now?"

An looked at the lock, then took Thao's badge. On the badge there is a code that matches the tunnel coordinates. She placed the badge in the small slot next to the voice code.

The light turns green.

Nam exhaled. “The witness was not me.”

“It's Thao,” An said. “She stood on the other side when they opened the way.”

The tunnel is half open. The water inside flushed out, carrying with it an earthy and metallic smell. There are thirteen measuring lines on the wall, the last line is colored red.

An looked at the red line. “Milestone 14 does not indicate that the water is about to rise.”

“What does it say?”

“It says the bunker is full.”

From deep inside the tunnel, a valve moved. This time, no one sent out a warning.

There is only one door that someone is opening from the inside.