Alfie Bloom knows he's about to have another dreadful summer. Not only will his inventor father be locked away in his workshop, but his best friend is visiting relatives abroad, which means he'll have no one. But then Alfie receives a strange letter inviting him to meet with a lawyer about his "inheritance." Alfie has no idea what they're talking about, but he goes along and makes a shocking discovery — someone has left him a castle! Hexbridge Castle is all his, which means no more long, boring summer days in his tiny house. He has a castle to explore! But being the owner of castle isn't all fun. Hexbridge conceals a centuries-old secret, the heart of a dangerous mystery that threatens to destroy Alfie's new home, his new friends . . . and everyone unfortunate enough to live within 1000 miles of the castle. Can this ordinary boy figure out a way to deal with this extraordinary challenge? Or will he follow in the footsteps of Hexbridge's last owners and succumb to a grisly fate?