Is this a good idea for a book?

I was thinking of writing a fantasy novel called SLAYER. which is about this guy named Conner Slate, a half-vampire teen. in the beginning of the story, he finds out that his ancestors were vampires, and that there was a war between good and evil. when the battle ended, the good vampires thought Dracula was dead, but many years later, they were wrong. since Conner is half-vampire, its "man by day. monster by night.", in other words, he transforms into a vampire, and takes down Dracula and his minions. and that's pretty-much the whole book. any questions?