Despite their vow to each other at the end of Once Every Never, best friends Clare and Allie once more find themselves in trouble-and travelling in time. Indulging in a low-key vacation at Glastonbury Tor, taking part in an archaeological dig while soaking up the sights of summertime England, the girls have promised each other: no time travel shenanigans; no involvement with dangerous Druids or villainous museum thieves; and definitely no weirdness about the fact that Clare is now seriously dating Milo, Allie's super-genius hottie cousin!