Three high school boys seem to have little in common, but one day they happen to sit next to each other at the back of the classroom. They soon become good friends, though they are always arguing or teasing each other. One day as they're jumping over the school wall, a thief falls out of nowhere and passes out right in front of them. He is holding a bag full of dollars. Not knowing what to do, they decide to take the bag first and think things out later. Meanwhile, Ji-hyeong is a rookie detective on his 100th day at the station, and is always busy trying to catch criminals ranging from drug dealers to petty thieves. Hearing that a usurer’s house had been robbed, he goes to investigate the case. But he gets orders to close the case, and he starts to get curious. He decides to continue investigating, in secret. Seong-hwan, Woo-seob and Jin-won have long since forgotten how scared they were at the beginning, and they are having a spending spree. Ji-hyeong’s investigation brings him closer and closer to them. Meanwhile, others are looking for the bag of cash too, and they are closing in on them fast.