I must say the plot of this movie made my brain twist trying to understand it.

So the whole 'mess' started when Ji Won supposedly died (we never got to actually see his corpse, though). The dad was about to kill Hyo Je but he got stabbed by old Mi Hee and the boy was pulled by her into the 'parallel' world (which opens only at each 25 years, right?). Because of that, young Mi Hee was arrested for 25 years (so convenient to the plot), and goes back to that house when she 'lives' the moment she stabs her husband. At that time, she met the priest who was actually her youngest son who had supposedly died.

So I wonder about 2 things:

1st: if the Priest was actually Ji Won, how was he alive if he had died? The only people of that family who entered into that parallel world was Mi Hee and Hyo Je. And for him to be that old (probably 25 years + the age he was when he supposedly died), he wouldn't have entered into that dimension (plus, their childhood friend was about the same age as him, which reinforces that probability).

2nd: what would really have happened at the very first time Mi Hee's husband tried to kill Hyo Je? Because the boy was only saved by old Mi Hee because she was already aware of everything that was going to happen and interfered on the situation, and that happened after her being imprisoned for 25 years for killing her husband. I just don't understand what's the beginning of that 'loop'.

What are your perspectives about it?

Wasn't the priest the other young friend of Hyo Je and Ji Won? The one that talked with Hyo Je when Ji Won was cremated? That's what I gathered from it. Especially with that ending, when he brought Hyo Je to older Yeon Hee from the present time.

As for the 2nd: there is no beginning of that loop. That's often a problem with time travel movies and shows that I somehow learned to ignore. 

 Kate:

Wasn't the priest the other young friend of Hyo Je and Ji Won? The one that talked with Hyo Je when Ji Won was cremated? That's what I gathered from it. Especially with that ending, when he brought Hyo Je to older Yeon Hee from the present time.

As for the 2nd: there is no beginning of that loop. That's often a problem with time travel movies and shows that I somehow learned to ignore. 

Gonna watch it again with that on mind. It may help me understand the plot a bit better. Thanks for your pov!

full movie short: there is door that connects all dimensions of different times every 25years which also involves disappeared people that went in into that door and never came back, they don't realize they disappear or died because they are still in their time. husband dies, kid disappears mom gets in prison after 25years come back to search for kid who she witnessed disappear. the door opens she gets in bam she is in loop that connects even past, she goes to find kid who disappears but it was him the alive one in past meanwhile the disappeared him went to look for his dead brother cuz he missed him. finally mother comes in contact with his disappeared son who is in older self I guess because of some story that he was in past (diff story it wasn't touched much and the kid was reincarnation so he was in his first form but still having presence memories) he explains the loop and tells her to go back to the his old old presence since he has smth to show but she is behind the door where her husband tried to kill the son, she decides to better go save him than go back to very past and she doesn't mind to begin this loop again. She goes in, accidentally kills husband, tells son to stay but as her young self called for her son she realizes something and takes the kid inside the loop only to come out quickly in present time. Since the kid has an illness and there was no medicine she brought him back to 25years later in case it was at least developed or being invented and he still has chance to live but since she is dying in that presence she left the kid to his past bestie who is now priest. the end,