This drama deserves the good reviews it has gotten because the acting is phenomenal and also the storyline is exciting.
We mainly follow Sanyeong(FL) and Haesang(ML). She is a hardworking girl and seems to be unhappy.... He is a folklore professor and notices that FL has a shadow - the shadow of a ghost, she is possesed by an evil one!
They work together to get rid of it and you are going to need to click on the next episode to see what will happen.
Be aware this drama shows a lot of TRIGGER WARNING
suicide but it is no S. but murder!!
I would not say that the genre is horror but mystery and thriller! :)
9.5/10 from me

PS: the drama will show how trashy humans are wbk