Jiyeon know Taemin for a long time, they was first neighbors later they was friends, in middle school they marked the more and more for themselves

but in highschool they path had to be separated

Jiyeon's father exposed himself somewhat menacing mafia boss, and along with daughter fled to another country

suddenly parting has left in the hearts of two young people a huge pain

Jiyeon deadly father fell ill, however, confessed before his death, a girl, a secret, whom she had to guard it like the eye in the head, it was a cipher and a floppy disk

This drive could have caused a lot of harm to many people, Jiyeon knew how important they are to the data, but did not know the drive is wanted by the mafia, but the disk itself is useless without the code which I knew only Jiyeon,

Jiyeon took care of a special organization that trained her in such a way that he could protect themselves, and gave her a special Defender Key, to protect her even at the cost of his life, so for more safety Jiyeon and  Key, came together, they had to try to live normally to not to attract suspicion

suzy is fall in love in Taemin on the day when she meet Taemin and start to live in his home after his father take care about her when her father die , but he dosn't show her that he could be interested her, he don't trust girls right know on that day when Jiyeon disappeared from his life without the word, without say him goodbay

Taemin and Suzy start to work in special company led by Taemin's father, they come to a new city, they start to new work, 

but what happend when one day Taemin meet Jiyeon again

will their relationship as they have on the past back?

will they start to fell to each other something more?

will Key is only Jiyeon defender?

what Suzy do when she find out that Taemin something connects with this girl?

what they do when some scary fact start to come out on the day lights?

will mafia find Jiyeon?

what troubles climbed in Taemin when he was after separation with Jiyeon on the past?

what connected with Jiyeon have Taemin troubles?

and what will by end of this story? will someone have to die that this four people start to live quietly?