"So when your friend will come?"ask Mrs Seo. She is excited. Really excited. It is the first time that Changbin say that he will have a group disscussion. She also think that Changbin have change a little bit.

"She is on her way,,by the way,, where is Chan. He sure is late."Changbin say.

"You're right, Chan sure is late." add Jisung.

"Ughh,, why do I sleep. They must be waiting for me." say Chan. He just wake up from his sleep. Living alone, there is nobody that will wake him up. He also forget to set up the alarm as his phone is died and he forget to charge it. He does not want to waste any time so he try to speed up but suddenly he stumbled into a man. Both of them fall.

"Watch out kid!!!" shout the man.

"Ughhh,, I'm sorry, it is my fault." say Chan.

With that, the man leave Chan behind while cursing. Chan quickly stand up when he see a parcel at  his feet. Without thinking he quickly take the parcel and slip it in his pocket.

"Where is Chan?" Sa Nae ask.

The other just shrugg their shoulder. Chan is not answering his phone. They start to feel uneasy. Just before they decide to search for him. Mrs Seo come in with Chan beside her.

"Thank you.." Chan say.

"Welcome,, go finish your work. I will prepare some food for you guys."

"We are sorry for troubling you.." Sa Nae say.

"Not at all" 

"Yahh.. why are you late? We are worry about you" ask Changbin.

"Yeah,, you also does not answer your phone." add Jisung.

"I am sleeping and my phone is out of batteries"explain Chan while smiling.

Sa Nae looks at them. How beautiful. Their friendship is really beautiful. At first, she thinks that they are a bunch of bad people. But it is not. They really care for each other. She smile. 

"So,, let's start our work. How about this, today we will search for mucous membranes and tomorrow we will finish with phagocytosis." explain Changbin.

"I thinks that a good idea. Right Jisung?" ask Sa Nae.

Jisung is shock when Sa Nae ask him. He quickly nod. The other just chukle at their friend behaviour.

~please...help me...

That voice again. It is the second time. Chan look around him but he can see anything.

"What's wrong with me" think Chan.

"Are you okay?" ask Changbin as he see that Chan is acting weirdly.

"Yeah.. there nothing." answer Chan.

"Woahh,, this topic is hard" say Jisung.

"Don't give up. It still early. What about you, Sa Nae?" ask Changbin.

"There's too many words. I can grasp the important point." answer Sa Nae while shaking her head.

~can anybody hear me

"Chan?" Jisung ask as he watch that Chan is not focusing.
"Yeah.. why?" ask Chan back.

"It just.. hmm .. nothing. Do you know anything about this topic?" ask Jisung trying to brush away his uneasy feeling.

"Oooh,, hmm let me think. Mucous membranes. It is human defence system. First of all it traps foreign material. It also the lining of respiratory tracts. Mucous traps debris and microorganisms and cilia move the mucous and debris up to the pharynx where it is swallowed. Beside that,mucous membranes is the lining of digestive tract for example asid hidrocloric or HCl in stomach kills all microorganisms." explain Chan.

The others are looking at Chan. Their mouth a wide open.

"Yah.. are you genius?" ask Changbin in disbelief.

"Do you think I'm stupid?" ask Chan back.

After a few hour, their work are finish thank to Chan help. Jisung and Changbin does not realise that their friend is genius. Sa Nae excuse herself to go back to her house. After thanking Changbin's mother, she walk toward the door accompany by the three friends. 

"Are you sure that you can go back alone. It is already dark" ask Changbin.

"Let me take you home. My house is just near with your house.It just one way route." say Chan.

"Are you akay with that?" ask Jisung.

"Yeah,, I'm fine with that. Sorry for troubling you." say Sa Nae while bowing.

"Not at all" say Chan.

"And thank you for today." add Sa Nae while smiling.

"It is a tiring day..." sigh Chan. He  just arrive at his house. He just think to sleep when he suddenly remember the parcel that the man left. He quickly take it out from his pocket. He sit on the chair and put the parcel on his table. After a lot of thinking, he decide to sleep without opening the parcel.

~help

  In a dark building, a man is beaten by a group of man. In front of them sit a man with a black beard.

"What are talking about? That thing is missing? Nonsense!" shout the man who is sitting.