If there's one thing 12-year-old Calix O'Shaughnessy is good at, it's bad luck. Divorced parents? Check. Eyebrows singed off after an unfortunate grilling incident? Check. Accidentally releasing an ancient Irish fire demon from the statue where it was imprisoned by St. Patrick 1,500 years ago? Check and check. Now the demon's on the loose, tearing through Savannah, GA, and it's up to Calix to take it down whether he wants to or not. Because it turns out, not only are fairies, monsters, and demigods real, but Calix is one of the heirs of St. Patrick, tasked with ridding the world of supernatural threats. Left with no other choice, Calix, his cousin, and his best friend follow a series of cryptic clues around Savannah in order to retrieve the pieces of an ancient Irish weapon known as the Demon's Bane, the only thing capable of defeating the demon. If they fail, the creature will raise an army of malevolent spirits and bathe the world in unholy fire. All of a sudden, regular old bad luck doesn't seem so bad after all.