Jin Isoo, the naïve heir of Hansu Group, gets into a fight with a stranger and Lee Gang-hyeon arrests him.

A model is found dead on a yacht; Jin Isoo gets his first murder case and investigates it with Lee Gang-hyeon.

The team starts an investigation into the model murder case and narrows down on a key suspect. However, other suspects come to light.

A famous painter is murdered in an art gallery, after which the team begins investigating people close to the artist; Isoo visits his childhood home.

Isoo goes to find the prime suspect on his own; after a struggle, he's able to make the arrest. However, he learns an unexpected truth just when he thought he had caught the culprit.

The team investigates an elderly person's death, but struggle to find a suspect; Isoo sets out to find the culprit on his own after learning new facts from the victim's family.