The O'Connell family (Lily - age 13; Tyler - age 11; and their parents) are vacationing in Ireland when they encounter an old man with a mysterious crystal that seemingly teleports them 1,000 years back in time. Unsure whether they have stumbled into a historical re-enactment, the family must befriend Rory, a timid local, battle a medieval tyrant named Ciaran and his henchmen, and figure out how to get back to the present, while Lily learns to use her newfound superpowers.