In an era of violence and corruption, Park Yeong-han, a humble detective, joins forces with Sang-sun, Gyeong-hwan and Ho-jeong to uphold justice.
A woman who can't trust people because of her ability to hear lies and a mystic composer who hid his indescribable identity, become involved in each other's lives to uncover the truth.
Young-ho doesn't have any dreams for his life. He has been studying for three years to enter a university. He decides to send a letter to his childhood friend So-yeon. But her younger sister So-hee receives the letter instead of her sick sister. So-hee writes back to Young-ho, pretending to be So-yeon. Meanwhile, So-hee takes care of her sick sister and also runs a secondhand bookstore with her mother.