The Ghost Knight by Cornelia Funke
I love this kid's author, so I grabbed this--her newest book--from the shelf without even knowing a thing about it. Very good, but not quite as captivating as her Inkspell trilogy. This one is about an 11-year-old boy who gets sent to boarding school and becomes haunted and hunted by a quintet of ghosts of have done the same thing to all of his male ancestors who showed up in that town. He takes them on with the help of his new best friend, her grandmother, his mom's boyfriend, and of course, the ghost knight of the title. Fun read (and only creepy if you're actually a kid reading it).