Episode 1.1: When the police discover skeletons on the train tracks at Mukyeong Station, Detective Do-won heads there while chasing a key suspect. (S1, ep 1)
Dead bodies in skeleton form are found in closed down Mugyeong Station. Do-won is on the case.
Seo-kyung finds the keepsakes that were gone 12 years ago at a murder scene in the skeleton.
Seo-kyung is murdered by the Mugyeong Station killer. Do-won sees someone unexpected at the station.
Do-won goes to World B and meets Seo-kyung. He's being chased as the suspect of a murder case.
Do-won A starts looking for victims of World A in World B, then has an unexpected encounter.
Do-won and Seo-kyung B are at odds over Kim Jin-woo, the suspect of the missing person case.
