Vampire: Mysterious Monsters (book three)

Maddie, Max, and Theo have come to the most haunted neighborhood in the most haunted city in America--and they're staying in the spooky Vampire House. While their father searches for evidence to prove its blood-sucker is fake, they set out on a search of their own through a city of the dead to a crumbling Voodoo shack. The Mattigan kids are on the case--but sometimes even the most clever plan can be a recipe for disaster.