I'm about halfway through my novel and I've reached a major turning point in the plot. It's a urban/modern fantasy. Half of the book is about my MC, a detective, gathering information on werewolves, vampires, and other beasties, trying to figure out where they came from and why they're out to kill us all. The second half of the book takes a major turn; the leader of these creatures returns (he was sealed away in an alternate dimension 1,000 years ago, along with all kinds of other "things") and declares war against all mankind. There's some foreshadowing and certain characters clue my MC (and the reader) in on what is about to happen, but I feel like the transition is kinda rough. It's peace one day and havoc the next, if you know what I mean. I suppose what I'm asking is, have any of you read a book like this and, if so, what did you think of it as a whole? I'm worried that the second half may disappoint readers who came to like the slow, technical approach of the first half. Or perhaps readers who enjoy war scenes and epic battles won't read through to the second half. There's a good mix of both throughout the novel, but the shift in emphasis is so sudden it troubles me.