Hwang and Hwang circle the same mystery from opposite ends, like two people trying to fold one fitted sheet. By the end you will know more about demons than you ever planned to. A thread left dangling since E10 gets tied off at last, neatly enough to make a librarian smile. A villain is offered a second chance, as if villainy were a bad haircut. Of all the things said this week, "This kind of thing is possible? Using skills?" is the one that will follow you to bed. Worth the time, and most of the opening song.