The Crown of Zeus, by Christine Norris
Thirteen-year-old Megan Montgomery's world is falling apart. Her father's promotion means leaving her whole life in New York behind. She finds herself transplanted to a huge house in the English countryside, with no one for company but the distant staff. Her new school only adds to her misery --neither the girls nor the teachers seem to like her. Then Megan meets three girls who actually talk to her instead of about her, and at first she thinks things are getting better. The girls seem more interested in the strange rumors that the house is haunted. Megan invites them to sleep over for the weekend. A discovery of a cryptic poem, a key and a diary written by the builder of the manor--an eccentric archaeologist turns the sleepover into a treasure hunt. Clues lead the girls to believe the Parthenon holds a great secret and suddenly they find themselves sucked into one man's version of Ancient Greece. The only way home is to find an object thought to be mere legend. If they survive that long.