Chapter 6 — Calls are not allowed to be hung up

As soon as Dan sat down in his chair, before he could put the notebook on the table, the phone rang. She picked up the phone in half a second, her heart pounding when she saw the familiar numbers from two previous calls appear on the screen.

— Operator, listen, it's Ms. Dan.

No voice. There was only a very soft breath, and then, complete silence, as if the child was covering his mouth with his own small hand. Dan understood immediately, this time he did not dare to make any sound, not even a whisper.

She recalled a technique she had learned in a training course on handling calls from victims being controlled, when the caller could not speak but could only listen. She lowered her voice to the lowest level, almost speaking into the child's ear.

— I know you can't speak. It's okay, you don't need to say anything. If you can hear me clearly, tap lightly on the phone for me to hear, like snapping your fingers on a speaker.

There was a silence of three seconds. Then, very quietly, a small "click" sounded through the line, like a fingertip touching the glass of the phone.

— Very good. Now let's play a game, like answering yes or no. One knock means yes, two knocks means no. Do you understand?

A knock.

Dan smiled even though no one saw it, a rare feeling of relief crept into the midst of the tension that had surrounded her for nearly two hours. She signaled Bao Ky sitting next to be quiet, he immediately understood and turned down the volume of his desk speaker.

— You're in your own room, right?

A knock.

— Is your uncle near you?

Two knocks, then a pause, then another knock, made Dan pause for half a second before realizing: perhaps his uncle wasn't right next to him, but he wasn't too far away either.

— You heard your uncle talking in the other room, right?

A knock, decisive.

Dan tapped quickly at the keyboard, recording each question and answer in real time, a small milestone of data that she knew would be more important than any lengthy recording, because it showed a coherent chain of logic rather than disjointed speculation.

— Does our house have an elevator?

Two knocks.

— So our house takes the stairs, right?

A knock.

— Is there a light on that staircase?

There was a longer silence than before, as if the child was trying to recall a specific image. Then two knocks sounded.

— The stairs are dark, right?

A knock. Dan notes on the side: maybe the stair light has been broken for a long time or the residents deliberately did not fix it to save electricity, a small detail but unique enough to distinguish it from dozens of other old apartments in the city with the same five-story architecture without elevators.

— You're very good. I just want to ask one more question, when you walk from your house down to the front door, do you have to pass any place that has a special smell, such as the smell of food, the smell of smoke, or something else?

A tapping sound, then a long pause, as if the child was trying to find a way to express something more complex than a yes or no answer was possible. Dan waited, without urging.

— Is it the smell of food?

Two knocks.

— The smell of cigarette smoke?

A knock, decisive.

Dan quickly wrote down in his notebook: the hallway or stairs had a permanent smell of cigarette smoke, it was possible that there were people sitting and smoking in the common area. She bit the tip of her pen, trying to picture a dark, cigarette-smelling staircase leading up to a fourth-floor apartment, where there was a wooden door with squeaky hinges.

There was a tapping sound, and immediately after, another soft sound entered the line, the sound of something rubbing continuously, steadily, like the sound of fabric or paper being crumpled. Dan strained her ears to listen, trying to distinguish the sound from the familiar background noise she had recorded from two previous calls.

— Where are you sitting, child, in the closet or under the bed?

A knock, followed immediately by another knock, made Dan understand that the child was nodding by tapping twice in succession for stronger confirmation, a small detail that Dan noted carefully, because it told her how the child was creating his own language to communicate in this situation.

She continued, her voice patient and unchanging even though every second that passed felt like a block of lead in her head. In the other ear is a child who has to use all his immature wisdom to answer correctly, and in the other ear is an adult who is trying not to let a single wrong question waste this fragile opportunity.

— How many floors does our house have, do you know? I will count from one to ten, knock when I reach the correct number of floors in my house.

— One... two... three... four...

At number four, a knock sounded clearly. Dan stopped for half a second, scribbled that number in the note box, feeling like he had just grasped an important piece in an unfinished picture.

— Our house is on the fourth floor, right?

A knock, more decisive and faster than before, as if the child too felt the small joy of successfully conveying a piece of information.

Dan was about to ask another question when the rubbing sound suddenly stopped, replaced by an unusual silence, different from the previous silences. She held her breath, sensing something was changing on the other end of the line even though there was no sound to confirm it.

— Son, are you still there?

There was no answering knock. There was only a long silence, then the line automatically disconnected, not because someone hung up suddenly like the previous two times, but as if the phone battery had just run out in the middle of the call.

Dan looked at the screen, the call duration displayed: one minute and forty-seven seconds, much longer than the previous two calls combined. She sat quietly for a moment, looking down at the hastily typed notes, where each question and answer was arranged into a coherent sequence: private room, uncle in another room, no elevator, dark stairs, fourth floor.

She reread the question and answer sequence from the beginning, wondering if she had missed any detail, if the way the child tapped twice for emphasis meant anything other than further confirmation, and if the final silence before the line went dead was a sign of something more serious than just a dead battery. She didn't have a definite answer to any of those questions, but she knew she couldn't sit still and wait for another call before taking action.

She closed the leather-bound notebook, stood up, and walked quickly towards the team leader's desk, where Anh Tuyet had just put down her headset after another call. She saw the look on Dan's face and knew there was progress without asking.

— Fourth floor, no elevator, dark stairs. — Dan said, his voice urgent but still maintaining the necessary clarity. — Do we have enough to narrow the scope of the other three residential clusters?

Anh Tuyet picked up the notebook and read quickly. Her face gradually brightened a little, although there was still the cautiousness of someone who was used to the fact that hope could disappear at any time in this profession.

— The old apartment complex in Vong Thuy alley has exactly five floors, and the elevator has not been in operation for a long time. The remaining two clusters are all ground-floor houses or one- or two-story boarding houses. If her information is correct, the highest possibility is that apartment building.

— What's the name of that apartment building?

— Lam Dien Apartment. Built in the early nineties, she remembers hearing her colleagues in Dong Lam ward mention it a few times because there were often disputes over shared electricity and water bills. Five floors, a single staircase, the elevator's automatic doors have been broken for decades and no one has fixed them.

Dan quickly wrote down that name in the notebook, underlining it twice, feeling like a big puzzle piece had just fit into its right place after many hours of groping in the dark of information.

— So now I can zone in on one apartment building, but I still don't know exactly which of those apartments is.

- That's right. Lam Dien Apartment has four apartments on each floor, counting the fourth floor alone, there are four different possibilities. But compared to the original eight hundred square meters, this is already a huge step forward.

Dan tightened the notebook in his hand, feeling like for the first time after three calls, that pale orange circle had begun to shrink into a touchable shape. She looked at the clock, it was twenty minutes past twelve, more than an hour and a half had passed since the first call, and with each passing minute she became more certain that she couldn't let this evening end with a file closed in silence.