The clinic was bustling with activity, with nurses running here and there carrying files and doctors walking around with patient reports in hand. One particular young doctor walked over to the reception desk, handing over a file to the nurse running administration.

"Done with clinic hours already, Dr. Park?" she asked, taking the file.

He nodded. "I'll just need to check up on a few of my patients, and then I'll close up for the day."

"Sounds good to me," the nurse said, reading through the file before closing it and putting it on the pile nest to her. She then got up and picked up the small pile, making her way out from behind the desk as Dr. Park signed the registry.

"Oh, and Dr. Park," the nurse quickly said. "You have a visitor."

A visitor? Why would he be expecting a visitor at the hospital?

He turned around, and the person sitting on one of the waiting room chairs made him smile brightly.

"Yoohyeon!"

"So, how's your mother?" he asked.

Yoohyeon smiled. "She's doing incredibly well," she said. "And so's Gahyeon, by the way."

He grinned. "I'm happy to hear that. So may I ask why you're here?"

"What, I can't drop by to meet my cousin once in a while?" she asked.

"You never have," he pointed out. "And your high school was closer to this hospital than your college is."

"You...were studying..." 

"I finished studying a few years ago," he told her, leading her into one of the exam rooms. Once inside, he closed the door behind them and folded his arms across his chest. "So, wanna tell me why you're really here?"

Yoohyeon took a deep breath, reaching into her bag and taking out a file. "Haejin," she softly said, "I sort of needed a differential for a case I'm looking into for an assignment."

"A differential?" he asked. "Wait, slow down. Tell me everything."

She shrugged. "Well, we have this assignment that we need to do," she explained as he leaned against the desk. "Our professor wanted us to investigate some old cases."

"So this is related to the one you chose to investigate?" he guessed.

She nodded. "A guy was murdered in his home, well, one of his homes," she explained. "The alleged killer was found right next to him, so he was arrested, convicted and sentenced to an asylum, where he eventually killed himself."

Haejin raised an eyebrow. "You used the word 'allegedly,'" he noticed. "Is it that you don't believe it to be true?"

She shrugged. "I'm not sure what to believe," she admitted.

He sighed. "Well, it all sounds very interesting, but I don't see how this has anything to do with me," he said. "You need a profiler, not a neurologist."

"Just hear me out fully!"

He paused and gestured for her to go on.

"I went to the place he was in and I looked through his files," she said. "A few things in his personal diary pointed to blackouts. Where he'd remember one thing and find himself somewhere else."

Haejin watched her for a moment, running his tongue on the inside of his cheek. "Give me the file," he finally said.

Yoohyeon gleefully handed over the file to his scoff and waited for a moment while he looked through it. He then looked up at her with a raised eyebrow. 

"This guy died in 1968," he stated. "No wonder he doesn't have a complete medical history."

"Well, can you help?" she asked.

He scoffed lightly. "You want me to diagnose a guy who's been dead for fifty years?" he asked. He sighed. "That might be harder than I thought. Its hard without a full medical history, and then comes the issue of actually meeting the patient to see if other doctors might have missed something-"

 "Then can you at least help me explain the blackouts?" she cut him off.

He sighed. It was hard to say no to her. He opened the file back up and scanned through it. "Well, the only thing I can think of is somnambulism."

"What?" she asked. "Please speak English."

"Sleepwalking," he clarified.

"Sleepwalking?" she asked.

He nodded. "I can understand blackouts, but finding yourself in places without knowing how you got there? That's classic sleepwalking."

"And it was never diagnosed?"

He gestured to the file. "It was 1968," he said. "They probably had no idea that sleepwalking could exist. They probably followed the stereotype of a sleepwalker needing to 'zombie' his way around. The idea that sleepwalkers could actually perform completely normal activities was unthinkable, forget attempting to understand it."

"So he was suffering from sleepwalking?" Yoohyeon repeated. 

He sighed. "But its only the start," he warned. "Sleepwalking is only a symptom, not a diagnosis."

"So what're you saying?" she asked. "That he had something else?"

He shrugged. "It's possible that it was set off by a disorder, schizophrenia or severe psychological distress," he suggested, "or it could even be caused by a neurological disorder. It could even be cancer."

"Cancer?"

He nodded. "Paraneoplastic syndrome could have been causing him to walk around in his sleep."

She cast her eyes to the ground, thinking. "So there's no way to know exactly what he had?" she asked.

He shook his head. "If they had an MRI machine then, they'd probably have scanned for tumors or something, but I'm not sure. This is all just speculation. It's hard to tell anything from an incomplete and ill-kept medical history like this." 

She thought for a moment. "There were signs that he was depressed," she said. "Could this be connected to it?"

He pursed his lips. "I'm not sure," he admitted. "It could be, but it also couldn't be related. Sometimes, symptoms don't always exist in conjecture with one another."

"Taekwoon wasn't the killer," she announced.

All five of them perked up on hearing that. Even Taekwoon meekly raised his head, his dark eyes filled with a slight shred of hope.

"W-what do you mean?" Sanghyuk asked.

"Taekwoon didn't plan to be there the night Lee Jaehwan died," she said, stepping forward and handing Sanghyuk the file. "He was a somnambulist, a sleepwalker."

The three black covered ghosts shot their heads towards her, surprised. "Did you guys know that?" she asked.

Hakyeon shook his head, turning to the cage to catch Taekwoon's eyes.

"So, what did you find out?" Sanghyuk asked.

"He was having blackouts," Yoohyeon said, pacing in front of the cage with all the guys' eyes following her. "He was finding himself in places he didn't remember going. This is sleepwalking."

"And you're so confident why?" Sanghyuk inquired.

"Because I got it run through by a neurologist himself," she said triumphantly. 

He stayed quiet, looking back down at the file. 

"Do you know what this means?" she asked, her voice rising.

"No, what?"

"It means that you guys were right!" she said. "Taekwoon didn't do it. He sleepwalked to the house." 

Sanghyuk raised an eyebrow. "You do know that that theory lacks a lot of details, right?" he said. "It's actually easier to believe that he did do the killing."

"Which was why he was convicted," she said. "Look, Taekwoon had something. Either he was going through severe stress, or he had something that was manifesting as sleepwalking."

She turned to him. "If he did have something, whatever it was didn't get the chance to take him before he offed himself." 

"So you think Taekwoon was sick?" Sanghyuk asked.

Yoohyeon nodded. "But the bottom line is that he didn't do the killing, which means that someone framed him. So he didn't kill Lee Jaehwan, someone else did, and framed him when he sleepwalked over to his place."

Taekwoon raised his eyes to hers.

She took a deep breath. "Jung Taekwoon is innocent."

It was precisely then that the bottom chain on Taekwoon's right hand shattered.