The Kaufman twins are happy to have their cousin Murray come to stay with them, but when they learn that their unusual relative is a vampire they will have to help him fight a pack of vengeful vigilantes
I read this when I was about 10, and I liked it a lot at the time. I just re-read it for Halloween, and I'm afraid that now I would probably only give it 2 stars; I still like the idea of it, but the style didn't click with me. I'm giving it 3 because I did enjoy it when I was closer to the recommended age group ;-)