Asking for money to his father imprisoned in jail, threatening a friend who became a murderer by mistake, stealing money from his friends... Ku Dong-hyuk (Kim Rae-won) is the worst scumbag you can ever imagine.

Living a low-life like a street dog, one day, Dong-hyuk gets kidnapped by a mysterious gang.

Being captured out of no reason, the gang trains Dong-hyuk in a secret and inhumane way repeatedly.

Dong-hyuk tries to escape but fails, which makes the training more harsh and cruel than before.

After finishing all the training, the gang orders Dong-hyuk to become a police detective as their secret connection.