The Enterprise focused on Human Development, but not in the way you might think.

SM Entertainment was at the brink at collapse in the year 2010. The Enterprise 'saved' it from going bust under secret conditions. Even today, only a handful of people were aware of the conditions, including EXO and F(X).

Even then, only Tao and Krystal knew the real truth. And they were well aware of the short span of their lives. They were also aware of the 'Last Mission'. But it seems there were still many facts which were not in their knowledge.

The gap in their knowledge was mainly conccerned with Baekhyun, and his drive to protect his little sister. Baekhyun could only remember part of his life, from the day he came into the Lee household when he was 14. Since that day, he had always been overprotective of his little sister, Junghyun. He even joined the SM Enterprise to become stronger.

When strange occurences begin to frequent Seoul, and all employees of SM Enterprise were given an extended holiday, the four youths were propelled into a frustrating life of hidden truths and difficult choices.