All Namjoon wanted was to find a place to hide so that he wouldn't get him daily beating from his bullies. What he didn't expect, was to accidently stumble across gang headquarters 

He just hopes that it isn't BTS. BTS is a group that you do not want to get involved with. They are a relatively new gang and yet have already overrun veteran gangs such as SUJU and EXO 

It just so happens that Namjoon does stumble across BTS