This drama was very unpredictable which is what got me continuing to watch it in a 3 day span. I liked it because there aren't a lot of episodes, so they packed everything into the 8 episodes they had, making use of all their time wisely. So there were no stupid scenes or useless side stories in play. When I first started watching, it was sort of slow because everyone is trying to find the sender of this letter, but once you get into it, it is no longer about a mere prank but life and death with the serial killer. I must say though that after they discover the killer, that's when the psychological games begin. Another side note, it helps that the people are very attractive, so that kept me watching as well ;)