"I Wanna Hear Your Song" is a mystery romantic comedy-drama about a timpanist Yi Young and suspicious tone-deaf pianist Jang Yoon. Yi Young suffers from insomnia after getting traumatized by what happened on 'the day' and comes across Yoon, who helps her remember. Yoon works several part-time jobs, such as a mover and waiter. Above all, he works proudly as an evening caller who soothes people to sleep by singing despite being tone-deaf. Yoon joins an orchestra as a pianist and meets Yi Young for the first time. Yi Young has nothing going for her. While being a timpanist for the orchestra, she is in the job market. Due to the trauma of witnessing a murder, she suffers from amnesia and insomnia. Thanks to Yoon's awful songs, Yi Young is finally able to sleep soundly. However, his songs make Yi Young remember the horrific memories she had forgotten. They try to put Yi Young's forgotten memories together and the truth about the murder case that traumatized Yi Young.