Harry Potter and the Vampire's Castle

Harry Potter is in a crisis- not a mid-life crisis, duh- he's also in a dilemma. A beautiful vampire is in Hogwarts and a certain Cho Chang pales in comparison to her. Will Hermione and Ron be able to make Harry see the right from the wrong; or will a strange occurrence occur at Hogwarts, one that has never occurred before? And what's Voldemort's evil plan this time?