"Brains Together" is a brain science comedy detective drama about two men who are anxious because they can't kill each other and solve crimes related to rare brain diseases. The neuroscientist Shin Il-il, who has a "very special brain", and the detective Kim Myung-se, who has a "brain of a victim", work together to convey a dreamy bickering chemistry, murderous laughter, and a message that resonates with people through a brain disease incident full of twists and turns. First, Jung Yong-hwa will play the role of Shin Il-il, a neuroscientist who was born with a silver spoon in his mouth and inherited a huge fortune. Shin Il-il is a man who has a "very special brain" and is not afraid of things that can feel burdensome at first glance, such as the law, money, women, loneliness, and death. He acts and speaks according to his own beliefs in everything. On the contrary, he will act ruthlessly and without mercy to people he thinks are trash. Cha Tae-hyun will play the role of the owner of the "altruistic brain" and detective Kim Myung-se who has a fatal kind charm. In the drama, Kim Myung-se is a character with a humane and kind personality, unlike the appearance of a corrupt detective who makes a living with a carefree macho attitude and a rough tone. Kwak Sun-young plays the role of Seol Su-jeong, a legal hypnotist investigator with a "cautious brain". In the drama, Seol Su-jeong is more sensitive to stress than others, and her heart will beat fast when she gives business instructions to her subordinates. She is a cautious and obedient person who does everything as long as she is told, but she experiences an incident that changes her personality 180 degrees. Ye Ji-won will play the role of Kim Mo-ran, the ex-wife of Kim Myung-se, who has a "brain full of sexual desire". In the drama, Kim Mo-ran is an owner who keeps changing men, cheating on her husband, and cannot control her sexual desire. She is a shameless woman who makes various requests to Kim Myung-se even after the divorce.