A high-school teacher in 1983 and a detective in 2015 join forces through their dreams to change the perilous fate of the woman they both love—30 years apart.
| Actor | Role |
|---|---|
 Lim Soo-jungYoon-jung / So-eun | Yoon-jung / So-eun |
 Cho Jung-seokJi-hwan | Ji-hwan |
 Lee Jin-ukDetective Gun-woo | Detective Gun-woo |
 Jung Jin-youngDetective Kang | Detective Kang |
 Lee Ki-wooDetective Lee | Detective Lee |
 On Ju-wanTeacher Park | Teacher Park |
 Lee Tae-riKang Seung-bum | Kang Seung-bum |
 Chun Sin-hwanBiology Teacher | Biology Teacher |
 Kim Bo-raChoi Hyeon-ju | Choi Hyeon-ju |
 Shin Ji-sooNice Schoolgirl | Nice Schoolgirl |
 Jung Woong-inKang Hyeong-chul | Kang Hyeong-chul |
| KKim Won-jinDetective Yeo-ju | Detective Yeo-ju |
 Im Ye-jinVice Principal | Vice Principal |
 Park Jun-gyuReal Estate Man | Real Estate Man |
 Kang Bo-minHostage Woman | Hostage Woman |
 Yoon Byung-heePlayer | Player |
 Han Hee-jungPresent Pickpocket Woman | Present Pickpocket Woman |
| LLee Sae-ro-miTeacher | Teacher |
 Choi WonSeogyeong High School Male Teacher 3 | Seogyeong High School Male Teacher 3 |