Three years went by between Vamp! 3 and Vamp! 4 -- Vamp! 4 was originally supposed to be a short story collection, but the sheer amount of time made him go for something larger in scope. It's a transitional novel in a lot of ways; the primary thrust of the narratives is to make the villains of the first three novels into good guys while introducing new villains. While the old villains were notoriously wacky, the new ones are Pure Blood vampires, who are living, breathing stereotypes...well, not literally, being undead, but they're the sort of one note dicks that wind up with the heroes teasing them for not knowing who Christopher Lee is. They're little more than opportunists anyway...the real villain in this book is mankind. Collectively.
A small village in the mountains is completely wiped out. One girl survives -- a girl with two small scabs on her neck. Rumors spread -- first that the village was attacked by vampires, and second that the girl herself is a vampire. She and her guardian soon find themselves fleeing an angry mob, only to be rescued...by vampires. "Don't worry, I'm a vampire," is not a line many books would contain.
This is ambitiously cross cut with flashbacks into the past of several major characters, and a number of extra twists laid on top of the big twists from the previous couple of novels. It takes a while to get everything moving, but it definitely moves when it gets there.
I will, however, admit that the primary appeal of the Vamp! series is the crazy fucking shit he pulls. The previous volumes brought us the flower growing under a guillotine that was soaked in blood till it became a vampire, and the vampire watermelon. This volume brings us a vampire spider (who wears punk/goth fashions in case he forgets and flings an extra leg out one of the handy holes), a vampire Chihuahua who insists he's a wolf, a vampire wolf who can't convince anyone he's not a werewolf, a girl gamer vampire with a collection of magic swords and move names based on Atari gaming classics, and, best of all, a vampire T-Rex.