Bu Tao drove his daughter Little Nai to her kindergarten class on his work-issued car. It wasn't a regular police car, but an unmarked car with sirens attached to the roof of the car.

"Bye sweetie, your mom will pick you up later, okay?" Bu Tao said as he urged his shy little baby girl toward her teacher.

Her large beady eyes pleaded to stay home, but he shook his hand and waved her to go. As she walked slowly toward the teacher and other children, he returned to his car and drove off to work.

In front of the police station, there was a bunch of men with bare chests and one woman doing pushups. The new training cadets saluted Bu Tao as he walked past them. Out of everyone in the police station, all the cadets admired Bu Tao the most. It was easy for the cadet to ignore him at first since he was so young, but after he knocked them all down during the sanda training, their level of respect for him grew. Bu Tao waved for the new cadets to ease up on the formality and walked directly to the cold case department.

"So, what information do you have for me?" Bu Tao asked one of the men who were in charge of cold cases.

"Sir, we found someone by the name of Yudan in connection with the Jia family's home invasion 8 years ago," the officer responded. "He and Mr. Jia used to go to high school together. Yudan is known to be in an underground gang that ran a gambling and lottery ring."

"Did he have any contact with Mr. Jia after high school?" Bu Tao probed. According to Li Yun, the two men should be familiar with each other.

"We aren't sure, none of the people we have talked to thought they kept in touch after high school. Mr. Jia went to college and Yudan dropped out before graduating high school."

"Were they enemies?"

"Everyone said they were friends who hung out together."

"Where is he now?"

"He's already in prison for robbery and assault. He's going to be released in a year. Yudan also had rape and racketeering charges, but none of the victims were willing to testify in court."

The more Bu Tao learned about the guy, the more enraged he felt. He was sure something happened between Yudan and Mr. Jia, "Did someone investigate Mr. Jia?"

"Mr. Jia does have strange spikes in his bank account, but the investigators back then assumed it was his hedge fund company."

"Is there any way to connect Yudan with the case?" Bu Tao thought it was likely that Mr. Jia had underground connections.

"That's going to be difficult. Most of the testimonies are from eight years ago and after the redistricting, many people have moved out of the area. The old rural police station didn't have the resources to properly store the DNA evidence either."

There wasn't much to work with, but Bu Tao assumed something must have happened that caused Yudan to seek out the Jia family, perhaps revenge? Bu Tao sent Li Yun the information about the case.

From the hospital, Li Yun read his phone message during his short break. His expression tensed looking at the pictures of Yudan and the victims in their last moments. He quickly closed out of the files on his phone and called Bu Tao.

"Any updates on the other cold cases recently?" Li Yun asked.

"Since most of them confessed, it was pretty easy for the Court to convict them," Bu Tao replied. "I'm impressed a simple university club could solve it. How did you convince Ju De?"

"Well, he was bored," Li Yun replied.

The development of the detective club had helped him with the exorcism. As long as he had some involvement, solving a case fulfilled the mission requirement.

Mission: Exorcise 100 spirits. 30/100.

After talking to Bu Tao, Li Yun took the day off to visit the Yide North-side Prison. Li Yun was used to holding cells, but it was his first time visiting a prison. He didn't think he would be shaken up, but the thought of seeing Yudan affected him more than he thought. He wasn't sure if there was the leftover yin energy in his body, but he felt rage and hatred whenever he thought about the guy.

Li Yun sat behind the glass barrier and studied a bulky man with hard eyes and bitter wrinkled lines around his mouth. Although he was only 35-years old, he was beginning to develop deep maniacal lines above his eyes. Yudan also studied Li Yun from across the glass barrier.

"Do I know ya?" Yudan asked impatiently.

Li Yun remained silent and slowly tapped his knuckle on the counter, creating a low and deep knocking sound that vibrated the air. The clock ticked forward, turning its arm around in full rotation as though it was following the rhythm of Li Yun's tapping.

"Look! This is my free time, what ya want?" Yudan was initially fine with a visitor since he was bored, but it looked like the visitor was playing him a fool.

"Do you believe in ghosts?" Li Yun finally asked.

Yudan snorted. "What sorta nonsense are you here to sell?"

"Not trying to sell you anything, but I have three clients who would like to speak with you. Would you like to hear from them?"

Yudan wondered what sort of message or code his former employer was trying to send, "Well, nothing better to do."

"The first client came to me at eleven as I was about to head to sleep. She was a pretty woman, with mesmerizing eyes and a flowing blue dress. She was cooking sizzling fish before she died. Do you remember the scent and sound of the sizzling fish?"

Yudan couldn't even remember the last time he had a decent meal.

"The second visitor came around one. He said you were a friend in high school."

Yudan frowned, wondering who the second visitor could be.

"Do you want to talk to him?"

"Sure, what ya want?" Yudan rolled his tongue, he was curious as to what this fellow was playing at.

"Hey Yudan, can you guess who I am?"

Yudan sneered. "The name tag said Mr. Li."

"You were the last to see me, I'm surprised you forgot so quickly. Eight years isn't that long ago."

Yudan tried to remember back eight years ago. There was only one incident.

"I really thought we were friends back then," Li Yun reminded Yudan in an eerie tone. "Yeah, I abandoned you back in high school, but it's a tough world out there. I did what I had to. But did you really need to stab me? You f**** bastard!"

Yudan momentarily froze, and then faltered back from his chair. The manner of speaking was almost the same as Gutao. "Cut this b******, who are you? Did some hoodlum send you here?"

"You don't remember laughing when the blood snoozed out from my guts or that you were having fun with my wife's corpse?"

Yudan looked a bit frightened. No one should have known what had happened. How did he know? Did a kid sneak in and watch what had happened? A witness?

"Did you know you killed my little girl?" Li Yun continued talking as eyes emitted dark yin energy.

Yudan remained frozen as though he was in hypnosis, the hatred in his eyes was the same as Gutao!

"Out of all of us, she was the most pitiful. Her hands were flailing around inside the womb, gasping for air. She clawed and knocked on her mother's womb, not knowing why she wasn't able to breathe. She drowned, with her murky eyes still open, looking eternally at the darkness, and never knowing the existence of light." Li Yun stared Yudan straight into his eyes.

"You f****** better be careful, my little girl will be knocking on your window every night."

Knock, knock, knock. The sound emitted as Li Yun tapped the glass barrier.

"Remember what I told you? I will f****** drag you to hell!" Li Yun suddenly got up and left, leaving a shaken Yudan sitting alone.

The warden was a bit confused, but he had seen lots of strange things, so took Yudan back to his cell. Yudan was quieter than usual, and his heart was beating in an unusual pattern. He kept thinking about the night he attacked Gutao's family. There shouldn't be any witness, but how!? At eleven, the lights shut off, but Yudan's body tensed.

"This is normal," he thought to himself, the lights were programmed to turn off every day at eleven.

Laying on his bunk, he tried to force himself to sleep. It was ridiculous, there wasn't such a thing as ghosts. Nevertheless, the only time he felt safe was when the warden walked by his cell. His eyes opened, and he looked out the window. After being in prison, his biological clock told him that it was almost one am. He suddenly felt a chill.

"Ah, bastard!" Yudan threw the blanket over himself and closed his eyes.

Later in the night.

Knock, knock, knock.

His eyes snapped open, but his body was paralyzed in fear underneath the cover.

"It's 3?" he thought.

Another knock at the window, he could feel someone's presence but he couldn't move.

"Move! Dammit!" He cried to himself, but his body wouldn't listen.

Underneath the cover, all he could hear was the knocking sound echoing in his ears. He shivered and mustered all of his energy to close his eyes, but the low knocking sound intensified from his window like the beating of his heart.