It is up there that she meets the ghost. He is guarding a pile of rocks known as the beacon, and when some archaeologists arrive to excavate it, they run into the strangest kind of obstruction. But it is not people the ghost fears, and when the real enemy finally reveals itself, the future of the entire human race is threatened. Only Aengus Og and his fairy kin can help now. But why should fairies bother themselves with human affairs?