During my BC (before children) days, in the late 1990s when we would regularly make our way to the movies, there was one we got to that has stayed with me. It's was a Gwyneth Paltrow flick about a woman living parallel lives contingent on her barely getting on a train or missing it. According to the film, Sliding Doors, this is the pivotal moment that determines the course her life from here on. I remember mentioning later to a colleague that this show was surprisingly fatalistic considering that it was presumably made for a largely secular western audience. Of course on hindsight, over 20 years later and after much consumption of screen sci-fi over the years, it's clearer that embedded in alternate/parallel universe stories are time immemorial preoccupations with the metaphysics of predestination, character and social determinism.
While I was binge-watching Train over the weekend, my mind would occasionally wander to Sliding Doors for their similarities but also for their differences. The former is clearly much more firmly fixed within science fiction multiverse theories while the latter is locates itself more simply as a "what if" kind of story. Parallel universe stories in my experience are as much about what's similar as it is about what's different. In every instance, it seems to me that there has to be a key, defining moment that causes that differentiation between worlds... or to put it in scifi jargon... a split or disruption in the space-time continuum. To understand how this particular multiverse works, I invoke a tree as the analogy to illustrate this. The trunk of the tree denotes the start of the key defining moment from where all the multi-universes branch off and at some point certain events branch off into their own separate trajectories. To my mind, it works roughly in the same way as alternate timelines. Star Trek 2009 is a clear example of how this works. The storytelling involves same people but their individual trajectory in the alternate universe/timeline is created when an anomalous event disrupts the original/prime timeline.
As much as the parallel universe side of things dominate much of the drama, this is still very much an OCN style crime show. There is injustice to be righted. There is a serial killer to be caught. There are morals to be pontificated. There are twists and turns to navigate all throughout even if the identity of the culprit comes as no real surprise.
The lead character Seo Do-won is a detective with a past. (Don't they all!) Do-won has a reckless streak and will do whatever it takes to nab the bad guys. He also carries a large chip on his shoulders. 12 years earlier, he stumbles upon evidence fingering his alcohol-dependant father for the murder of another man -- the father of the woman he grew up with and has more than brotherly feelings for. She, Han Seo-kyung, has also become a crime fighter in her own right, a compassionate prosecutor who wants more from their push-pull relationship. His branch station chief, Oh Mi-sook, who ends up raising both of them was the lead detective for that case. To protect the young people in this seemingly ill-fated connection, she convinced him then not to turn in the incriminating evidence. Fortunately but still tragic for all concerned, Do-won's dad was fatally wounded in a hit-and-run during that same night and so the murderer from 12 years ago was never officially caught and identified. As a result of the spectre of this family melodrama hanging over his head, Do-won's feelings for Seo-kyung are complicated by obligation, guilt and genuine affection.
One night when Do-won's dogged pursuit of a suspect ends up in a disused section of a railway line, he stumbles onto a poorly concealed serial killer's grave. This find initially turns up the skeletal remains of four unknown women and some familiar-looking jewellery. As the investigation into these serial murders deepens, Seo-kyung gradually comes to the conclusion that Do-won's dad might not have been her own father's killer after all. The answer, it would appear lies with the now abandoned Mukyeong Station and as she gets too close to the truth for comfort, Seo-kyung is permanently silenced by someone who appears to be the perpetrator.
As the distraught Do-won begins to put the pieces of the puzzle together, he is led to a mysterious train that takes him to a parallel but somewhat antithetical Mukyeong where his other self, also a detective, is a fugitive on the run for allegedly gunning down a known drug-dealer. It is at this juncture that the two selves while in pursuit of the serial killer cross over into the one another's universe. Do-won B is quite a different beast altogether supposedly because 12 years earlier, he arrived in time to save his father from the hit-and-run accident. Unlike Do-won A, Do-won B did not meet Seo-kyung and save her from her abusive step family. In the B universe both grew up separately and differently. As far as Seo-kyung B is concerned, Do-won is the son of the murderer of her father.
Complications ensue but Do-won A is consoled to see his beloved Seo-kyung alive in another iteration in this parallel world where his other self is a bitter, resentful junkie. This Seo-kyung only know Do-won as the son of her father's killer. She is immediately hostile and rejects his overtures of goodwill. Wisely he assumes the identity of the other Do-won to investigate the case. The people around him while they notice personality differences, are too busy and too blase to ponder the reasons. Or so we're told. Seo Do-won in universe B is not well-liked and so no one cares enough to probe. Besides, his colleague seem to prefer the change. Other mysterious occurrences emerge while Do-won A navigates the differences in the parallel world which inevitably lead back to the identity of the serial killer.
The show does a reasonable job differentiating the parallel Mukyeongs through Fringe-inspired use of special effects and subtle costume changes. I am surprised that there's a general lack of curiosity on the part of the other characters about the different Do-wons especially when the two selves find themselves in the same place at last. Perhaps we are meant to take it as a statement about how unobservant people generally are. ;)
Comparisons with The King: Eternal Monarch are inevitable considering the subject matter. Happily, this drama has the better script and deals with the parallel universe trope in a much more cogents and consistent fashion. Overall, it is better conceived, better thought through and better executed. It doesn't have the flash of The King to be sure but the storytelling is far superior. The 12 episode format undoubtedly helps. Not a lot about The King makes sense to me (big on ambition but little on plotting) but the character of Lee Geon is the most problematic of all. He comes across more a mannequin dancing to the requirements of the script than a relatable character.
A major part of why this show works has to do with Yoon Shi-yoon's wonderfully nuanced performance. Watching him in this is a joy. While the acting across the board is a mixed bag, Yoon Shi-yoon is in a class all by himself bringing both Do-wons with their subtle differences to life. Do-won A is the less embittered of the two and so the impact he has in his world differs accordingly. What both Do-wons have in common is an inhuman drive to get to the bottom of things. This will to persevere in the face of obstacles and survive incredible odds is what it seems makes the parallel 'verse hopping possible.
Do-won's A appearance in Universe B reminded me of Frank Capra's It's a Wonderful Life. As he interacts with different iterations of people he knows in a different world, it is clear that his original trajectory had an enormous difference not just for him but to the people he rubs shoulders with from that time onwards. In the case of Jin-woo, Do-won's distinct presence in both worlds had huge ramifications for what happens to Jin-woo. What of course he didn't know at the time was how decisions made by persons in the different universes led to different outcomes which also had their own ripple effect on his life and the subsequent choices that he made. Do-won is not the first parallel universe traveller and each leaves their mark. It isn't a completely clear cut case of destiny at work or some kind of cosmic predestination because the show seems to point to human agency being a primary factor causing ripple effects. Undoubtedly there are fixed points -- from the basic fact that the same people exist in both worlds and often involved in similar activities. However it is clear that neither universes are immutable or static.
The most unexpected feature of the show is that it attempts to offer some explanation of how the world hopping works. I don't normally expect that sort of thing for a K drama. Although the magic train works during the magic rain, there's apparently more than one magic train. The show also speaks to the importance of individual autonomy. It makes a clear case for the notion that the presence or absence of a person can make a whole world of difference.