Siheyuan (traditional courtyard house): Starting with the Korean War, returning home to take charge

The investigation began on the third day.

Old Sun and his team started by checking the research institute's own equipment. They disassembled each of the old Soviet-era machine tools in the workshop, one by one. Ma Yuejin squatted beside them, helping to tighten the screws, sweating profusely, his work clothes soaked through and clinging to his thin shoulder blades. When they got to the fourth machine, he found something in the corner of the control box—a small gadget, glued on, not much bigger than a fingernail, with a translucent plastic shell and coils of metal wire inside, as delicate as a watchmaker's work.

Old Sun used tweezers to pick it out and examined it under the light for a long time.

"Another one."

His voice was very soft, as if afraid of disturbing something. Ma Yuejin leaned closer, saw what it was, his face turned bright red, he wanted to curse, but didn't know who to curse, and finally squeezed out a sentence through gritted teeth.

"Damn it."

Old Sun put the bugging device in an envelope and made a note of it in his notebook. He Yuzhu stood beside him, looking at the machine tool that had been dismantled into pieces. The casing was piled on the ground, the circuit boards were spread out on the table, and the wires hung down like severed limbs. He remembered when the Soviet experts withdrew that year, they had dismantled equipment in the same way—but back then they were afraid the Soviets would take away the technology, now they were looking for the "gifts" they had left behind.

The research institute searched the equipment for three days and found two items. Old Sun sealed the envelope, wrote a number on it, and put it in the cabinet and locked it.

"Go outside to investigate tomorrow."

He Yuzhu didn't look at him, staring out the window. The sky was overcast, the clouds hung low, and the leaves of the jujube tree in the yard were turned over by the wind, revealing their grayish-white undersides.

"Start with the important things."

Old Sun flipped through the notebook, his finger leaving a mark on the paper.

"An air force radar station, a naval communications station, and a factory that makes vacuum tubes. These places all have Soviet equipment, which has been in use for several years."

He Yuzhu tapped his knuckles on the windowsill, but no sound came out. He remembered the year he went to Moscow, when the Soviets tried to fool him with technology from ten years ago, and he cursed them in Russian before leaving. Now, that technology had become listening devices, hidden in radar, radios, and machine tools, listening for who knows how many years.

"Hurry up. If you're too late, they might be gone."

Old Sun nodded and left.

The footsteps in the corridor faded into the distance, but He Yuzhu was still standing by the window. It was getting dark, and the streetlights were still off, casting an ambiguous light in the courtyard, as if viewed through a layer of dirty glass. He touched the key in his pocket; it was metal, cold, heavy, and digging into his palm.

He recalled the three listening devices: translucent plastic shells, neatly wound coils, and solder joints so smooth they looked machine-welded. Soviet-made things—meticulous, durable, and silent. Even as you looked at them, they were listening.

When Lao Sun returned from the radar station, it was already completely dark. He Yuzhu's office door was open, the light was on, and several documents were spread out on the desk, but he wasn't there. Lao Sun stood at the door for a while, then heard footsteps at the end of the corridor. He turned around and saw He Yuzhu coming from the archives, the key still hanging in the lock.

"You found it?"

He Yuzhu walked over, took the key out, and put it in his pocket.

Old Sun followed him into the office and closed the door behind him.

"There's one hidden inside the radar's power module. It's the same one we found."

He Yuzhu sat down in the chair without saying a word. Old Sun also sat down, the chair creaking. He took out a cigarette, tapped it on the table, lit it, took a drag, and slowly exhaled. The smoke dispersed under the light, blurring his face.

"No one at the radar station knew about it. The equipment came with the main unit; it was already inside when it was installed. It was the last batch of equipment before the Soviet experts left, arriving in 1959."

He Yuzhu pressed his hand on the table. It was 1959, before the Soviet experts withdrew. They were teaching people how to use radar while simultaneously installing listening devices inside. What did they want to hear? How much did they hear? Only they themselves knew.

"Where's the communications station?"

Old Sun stubbed out his cigarette, twisted the butt in the ashtray, and then twisted it again.

"We also checked the communications station. There was one in the radio, in the power module. It's the same as the one in the radar station."

He paused, lowering his voice slightly.

"But there's something else going on at the communications station."

He Yuzhu looked at him. Old Sun stood up, walked to the window, turned his back to him, and looked at the night outside.

"The soldier on duty said that in recent months, the radio would sometimes turn on inexplicably. We checked the records, and it wasn't them who turned it on."

He Yuzhu tapped his knuckles on the table. The sound wasn't loud, but it was clearly audible in the quiet office.

"Has someone tampered with it?"

Old Sun turned around, but didn't sit down; he stood by the windowsill.

"It's not certain yet, but it's very likely."

He paused for a moment.

"We've already sealed that radio. We'll see what happens next."

"What about the electron tube factory?"

"Let's go tomorrow."

The electron tube factory in the south of the city was older than He Yuzhu had imagined. Most of the white paint on the red brick factory buildings had peeled off, revealing bricks of varying colors underneath, some black and some red, like a faded old chessboard. Only half of the slogan at the entrance remained; the character "劲" (jing, meaning energy/exertion) in "鼓足干劲" (guzuganjin, meaning to work hard) was missing its last stroke, making it look like the character "功" (gong, meaning achievement/merit).

The factory manager, surnamed Li, was in his early fifties, thin, and walked with a slight drag on his left foot. He stood at the factory gate, rubbing his hands together; his knuckles were large, and his fingernails were stained with indelible grease.

"Director He, Section Chief Sun, we've checked here and found no problems."

Old Sun didn't reply and led his men inside. He Yuzhu followed behind, hearing Factory Director Li sigh behind him and then catch up, the sound of mopping the floor rustling on the cement.

The machines were running in the workshop, and the workers were working with their heads down. Sunlight streamed in through the windows, swirling dust particles in the beams of light. The air smelled of machine oil and rust, a stuffy, suffocating odor that made one's throat tighten. Old Sun walked to the old Soviet-era machine and squatted down to examine it. Russian writing was printed on the exterior, and much of the paint had peeled off, revealing patches of rust beneath, like spots of mildew.

"When did this equipment arrive?"

Factory Director Li stood behind, unsure of what to do with his hands, sometimes putting them in his pockets, sometimes letting them hang down.

"It was brought by Soviet experts in 1958, who said it was the most advanced at the time."

Old Sun stood up and waved to the people behind him.

"dismantle."

Two technicians came over with tools and squatted down to remove the casing. The screws were badly rusted; they tightened them with a wrench, then paused, the sharp, piercing sound of metal scraping echoing through the workshop. He Yuzhu noticed that the machine noise in the workshop had decreased, and the workers looked up in their direction.

After the outer casing was removed, the inside was filled with circuit boards, vacuum tubes, and coils. Old Sun shone his flashlight inside, and the beam of light swept across the components, stopping at the innermost part.

"this."

The technician removed the module and pried open the cover. Inside lay a bugging device, with a semi-transparent plastic casing, a neatly wound coil, and smooth solder joints, as if machine-welded.

Factory Director Li's face turned pale.

He opened his mouth as if to say something, but a dry, hissing sound came out. He looked at the bugging device, then at Old Sun, his gaze shifting uncertainly before finally settling on the ground.

"How...how could there be such a thing?"

His voice was weak, like smoke scattered by the wind.

Old Sun didn't answer, and put the bugging device into the envelope.

"This equipment, seal it up. No one is to touch it."

Factory Director Li nodded, rubbing his hand on his pants, then rubbing it again.

Old Sun turned around and looked at He Yuzhu.

"There's one more. In another workshop."