WHATS THE NAME OF THE 책

I am watching the series on tv but I see so many people on 페이스북 talking about A . And i'm afarid to even go in a chat room because I dont wunna know before I watch them all. But I really wunna talk about the show. So i was thinking I could read the 책 so I could be caught up. and wont get mad if i found something out too early