Chapter 11 — The Journey of the Missing Bronze Drum

The silver car parked across the street, about fifty meters from the gate of Diem's dormitory, first appeared on Tuesday night, when she came home after a late work session with Hai. She didn't pay attention right away — a car parked on a public sidewalk was not unusual.

It appeared a second time on Wednesday night, same location, same parking angle, although the license plate was different - a detail that only someone with a habit of meticulous observation like her would notice: same car, same small scratch on the right front bumper corner, but the license plate had been changed. She stood on the fourth-floor balcony looking down for a long time, trying to convince herself that her visual memory, which was very reliable when analyzing antique patterns, was playing tricks on her in a completely different context — a crowded street, dim lights, dozens of cars of the same color and model passing by every day. But that scratch, the distinctive distorted shape of a fingerprint, could not be the second coincidence in the same week.

Diem did not say anything to anyone, including Hai, for the first two days. She wanted to be sure she wasn't building up an unfounded fear from fragmentary facts. But Thursday night, as she walked home from the parking lot, a strange text message appeared on her phone, sent from an unregistered number.

"There are some doors that, once opened, cannot be closed again. You should think carefully before opening any more doors."

Diem stood frozen in the middle of the empty parking lot, her hand clutching her phone, her eyes quickly scanning the surroundings. Nobody. There were only high-pressure lights shining down on the silent cars, and the sound of the wind blowing through the trees on the side of the road.

She took a screenshot of the message, then called Hai.

"I just got a warning text," she said, trying to keep her voice calm even though her heart was still beating fast. "And there was a car that followed me two nights in a row, changing license plates between appearances."

Hai's voice immediately changed to a serious state, without any trace of his usual joking. "Where are you?"

"Parking lot near the house."

"Don't move, I'll be right there. Go into an area with many people, under bright lights, don't stand alone in a hidden place."

Fifteen minutes later, Hai showed up, accompanied by a technical colleague carrying a wave detector. They checked around Diem's parking area first, and in less than five minutes, the device beeped steadily as it scanned under her car.

"There's a GPS device mounted here," the technician said, emerging from under the car, holding a small black block with a magnet attached. "Commercial type, easy to buy, not a specialized product from any government agency, but accurate enough to track daily travel routes."

Diem looked at the small device in the technician's palm, a cold feeling spread throughout her body, not because of simple fear, but because of realizing the seriousness of what she was facing. This line not only knew she was investigating. They knew her well enough to find out what car she was driving, and knew her schedule well enough to attach the device when she wasn't paying attention.

"Since when?" she asked, her voice hoarse.

"It's hard to determine exactly, but based on the layer of dust around the device compared to the surrounding car body, I'd guess about five or six days ago," the technician replied.

Hai did a quick calculation in his head. "Five or six days ago, right after I visited Hoai Co Duong."

The two looked at each other, without needing to say out loud what they were both thinking.

"I'm not sure it's Ta Bach Son," Diem said, although her voice was not very convincing even to herself. "Maybe it was just a coincidence of timing. Maybe the network was following me before, I just didn't pay attention."

"Maybe," Hai agreed, but his eyes were still full of doubt. "But whoever it is, the message is clear: they know you're getting close, and they want you to stop before it goes too far."

The technician packed the tracking device into an evidence bag, preparing to take it back to analyze the serial number to see if he could trace the place of purchase, even though all three understood that the likelihood of success was not high with this common type of device.

"I'll check the device's connection history further," he added, turning the small plastic block in his hand under the streetlight. "This type often uses a paired sim, sending coordinates to a phone number or a server address via the mobile network. If we are lucky, we can trace the phone number receiving the signal, although the person buying the sim must have used fake documents or a junk sim without the owner's registration."

"Just try," Hai said. "Even if the probability is low, every little lead is worth pursuing at this time."

Diem stood silently looking at her car under the high-pressure lights. The familiar feeling of security that the car once brought had now disappeared, replaced by a new, heavier vigilance, clinging to her like a shadow that could not be removed.

"Do you need to move temporarily?" Hai asked, his voice filled with genuine concern. "I can arrange a secure apartment through the unit."

Diem shook her head, although there was still a trace of fear in her heart. "If I move now, they'll know they've succeeded in scaring me. I don't want to show them that." She took a deep breath, trying to regain her familiar composure. "But I agree that extra precautions are needed. You can change your daily travel schedule and avoid fixed routes."

Hai nodded, but still stayed a while after the technician left, making sure Diem got inside the house safely. Standing at the door, he hesitated for a moment before speaking further.

"Diem, I know you don't want to appear weak under pressure. Neither do I. But if there's anything unusual, no matter how small, you call me immediately, regardless of the time. Don't handle it alone, even if you think you're capable."

Diem looked at him, a strange feeling of warmth crept into the midst of the overwhelming insecurity, the feeling of knowing that she was not completely alone in this investigation, different from the feeling of loneliness twelve years ago when she was alone carrying doubts about Mr. Trac's death without anyone really trusting her to listen.

"Thank you," she said, her voice rare with sincerity. "I will call."

Before Hai could turn around and leave, Diem called him back, another worry had just risen in her mind. "There's one more thing. If they've followed me to this extent, I'm worried about the other people involved in the case — Chu Vinh Tru, Doanh in Go Lang Uyen, and Uncle Khoat. They're not trained to realize they're being watched like me."

Hai nodded immediately, his expression showing that he had also thought the same thing. "I will send someone to discreetly keep an eye on the Go Lang Uyen area for a few more days, without fanfare, just enough to detect if there are any unusual movements. As for Mr. Khoat, I will call to remind him to be careful, even though I know that someone like him who has been in the profession must have taken his own precautions."

"Thank you for thinking of that before I could finish my sentence," Diem said, her voice a little relieved.

"That's the least I can do," Hai replied, starting the car. "We are dragging many innocent people into danger just because they happen to be close to the truth. Protecting them is our responsibility, not a choice."

After Hai left, Diem locked the door carefully and checked each window before sitting down at her desk. She opened her laptop, not to continue her work, but to review the screenshot of the warning message again.

"There are doors that, once opened, cannot be closed again."

She typed that sentence into a new document, saved it as evidence, then added a personal note to herself, not to submit a report, but as a reminder to herself:

"The door opened twelve years ago. I don't intend to close it again."

She turned off the desk lamp, but didn't go to sleep right away. She sat in the dark for a long time, listening to the fading sound of traffic on the street, trying to imagine the face of the person who sent that text message — whether it was Vu Bach Long, the man she had only seen through binoculars once, or some other link in the chain whose existence she did not yet know. Whoever it was, the message had achieved part of its purpose: it made her scared, truly scared, for the first time since the beginning of this case.

But that fear, she realized as she sat alone in the dark, did not make her want to back down. It only made her more certain that she was on the right track — after all, no one wasted time threatening someone who was going astray.