The film Train to Busan never really offered a full explanation on how the
zombie outbreak started [check our film review]. Aside from the
phone call between Seok-Woo and his analyst, plus the mention of a chemical
leak in a nuclear plant in the prologue, not much else was revealed.
We can now discover how it all started in Seoul Station, an animated prequel to Train to Busan that explores the origin of the outbreak. It's also driven by the same director, Yeon Sang-ho, whose directorial roots actually came from animated films such as The King of Pigs and The Fake.
Seoul Station follows the story of a father searching for his runaway daughter, Hae-sun, in the midst of a government lockdown. Hae-sun, who has just ended her relationship with her boyfriend who forced her into prostitution, leaves the shabby inn they were staying at near Seoul Station. That's where she sees people being attacked and becoming the attackers. The trailer also hints that the outbreak began with an infected homeless man. As to how, we'll find out soon.
Rumors say that Seoul Station will release locally this October. We'll update this as soon as we find out more information.