Story is interesting but you can't ignore dumb decisions made by leads. First 10 ep were good, a solid 8/9 then one particular moment changes the perspective of how you see things and start questioning things. Then not so perfect story falls apart and you can't enjoy it quite well. Major spoilers ahead!!!
Now talking about the moment. Gu sanyeong was inside line of prohibition on a rainy day. Then evil spirit threatens her to kill her mom, then she freaks out and goes out to save her.
Another dumbest of them all moment goes to FL's mother when she listens to evil spirit and goes to kill yeom haesang. Then comes back and leaks info about thumb search and asks to spare her daughter. Lets assume that her brain got fried after all the shock. That way its better. Other minute things, maybe they used to give certain thrill to audience. Yeom haesang, the one who has most knowledge about ghosts among those alive uses subway, where he has no control over doors. When older detective got killed, he says dont open door until I get there.
Plotholes: 1) the very purpose of a horror story is how to contain/get rid of evil spirit. They should be clear and fault proof. In this there are 2 methods. One method, which includes 5 objects and name is stupid no matter how I see it. Evil spirit needs 5 objects to take over human body, and leads need them to seal evil spirit. This way spirit wins everytime, the moment they found objects it takes over their soul, and if they get objects/name wrong they die.
2) they found the skeltal remains/5th object, spirit didn't touch this object yet, but still took over Gu sanyeong. Existence and someone finding out the objects is enough?
Despite all the complaints I enjoyed most part of the drama. Acting is great and background score is refreshing. Na byeong hui (evil grandmother) is the only consistent thing lol. She's trash alive or dead. One thing for sure is evil spirit is genius and other characters are dumb.