"So what should we do, then?" Murong asked, "Maybe the person who put it here will think the camera is broken and come to fix it. Then we'll catch them!"

Ye Fei gave Murong a deep look and reluctantly said, "If all criminals thought like you, the world would be peaceful."

Murong frowned, "What is that supposed to mean, Ye Fei?"

"It means you're very... kind hearted." Ye Fei was going to say Murong was foolish, but he knew she had very touchy self-esteem, so he switched to a euphemism.

Unexpectedly, Murong's face turned red as an apple, which made her look adorable. "Humph! I am not that kind!" she said coldly, giving Ye Fei a sidelong glance.

Ye Fei opened Lin Qingwan's wardrobe and looked inside for a few moments. "Let's go," he said in disappointment eventually.

"Huh? Go where?" Murong asked in amazement.

Ye Fei thought for a while and said, "I had deliberately broken the camera inside this wardrobe earlier. A full day has pa.s.sed, but no one has repaired it. I a.s.sume whoever planted the cameras hasn't come to retrieve the footage yet."

"Isn't that a good thing?" Murong said. "Perhaps no one has the footage of Sister Qingwan changing clothes yet."

Ye Fei frowned. "Perhaps, but there's a downside. If I'm right, it means there must be a traitor inside this villa. We have to find a way to flush them out."

"But before that, we need to pick up the signal." Ye Fei continued, "Lin Qingwan rests at home at night, so if I'm not mistaken, these cameras should start sending and receiving signals at night. At night, we can find where they're transmitting to."

Murong looked at Ye Fei with surprise. "What are you talking about, Ye Fei? How come I don't know about any of this, even as a police officer? How do you pick up the signal?"

"You may be a police officer, but you aren't the brightest police officer," Ye Fei sighed. A pillow flew towards his face.

"Ye Fei, I'm warning you, call me stupid again and you'll regret it!" Murong shouted at him.

"OK, OK, I won't." Ye Fei raised his hands in surrender. Then he said more seriously, "This camera has a single signal and its receiver is on the same channel. We only need a simple signal scanner. If we can tune into the right frequency, we can find the receiver."

Murong didn't understand any of it. She frowned at Ye Fei and said, "Just tell me plainly what we need to find this person."

After a moment's silence, Ye Fei said, "A radio or a pager."

"Radio or pager? Where can we find antiques like that?" Murong said. "I could go back to the police station and get a radio set. I don't know how to use it, but I bet you can."

"No need, a phone is actually enough."

Ye Fei continued to explain, "Any mobile phone is a signal receiver. It also has a location tracking function. Ordinary people don't use these functions, but in reconnaissance operations these things are particularly important. If there is no mobile phone available, we often need to make a makes.h.i.+ft transmitter by ourselves."

"Wow, Ye Fei, you're so knowledgeable! Is that how you make a cell phone bomb? Like those where you press a b.u.t.ton and the bomb explodes? That's awesome!" Murong exclaimed, looking at Ye Fei with a kind of admiration.

"It's not too complicated. In fact, the principles are very simple; a high school student could make it. However, censors.h.i.+p is very strict in this country, so common people don't have access to that kind of information."

Ye Fei paused, closed his eyes, and remembered the battlefields of Iraq.

Even 10-year-old children could make mobile phone bombs abroad. It was a terrible place.

"Ye Fei, I read your file, but it's not clear when you became a soldier. You know so much.. you must have killed many people on the battlefield."

Murong continued staring at Ye Fei with admiration. She was now getting more interested in his combat experience.

"Wherever in the world there's a war, Falcon's shadow is present." Ye Fei gave her an ambiguous answer. The subject involved state secrets.

Murong was just an ordinary cop. It was best if she didn't know these things.

When Murong realized Ye Fei was not willing to say anything more, she grumpily threw him her phone, "Do it. I'd like to see how you pick up the signal."

Ye Fei took Murong's phone and found that it was already connected to Lin Qingwan's WiFi. He pressed the screen a few times and opened a strange website.

Murong saw letters she didn't recognize, "What's this? I can't read any of it."

Ye Fei smiled and said, "This is Arabic. It's a website run by terrorists in the Middle East. This is a good website to download certain applications that can't be downloaded through normal channels. A comrade told me about it."

Ye Fei downloaded a special application to detect the signal.

"The world is full of wonders." Murong stared at Ye Fei. She had never heard of software like this.

Ye Fei walked around the room with the phone, making adjustments to the program's settings. After a short time, the phone started beeping and a white dot appeared on the screen.

"That's the frequency!" The intensity of the beeping gradually changed as Ye Fei slowly walked in the room. The closer he got to the source, the faster the beeping became.

Ye Fei went down the stairs to the ground floor and over to a utility room. "The receiver is in there."