[3][4] Jung-min is the new detective assigned to a neighborhood where a serial killer commits murder every rainy Thursday.

Laidback and blundering at his job, Jung-min is actually secretly studying for a civil servant exam to get away from his boss who's always picking on him.

To make matters worse, Jung-min's mother who happens to be the president of the women's association is leading the protest.

Because of the reward for the killer's capture, Young-seok is trying to catch him well, and his natural detective skills lead him to always arrive at the crime scene one step ahead of the police.

Jung-min absolutely cannot let Young-seok solve the case and take away his chance of a lifetime, so a rivalry forms between the two as they both race to catch the killer.