Best friends Clare and Allie once more find themselves in trouble-and travelling in time. Taking part in an archaeological dig at Glastonbury Tor in England, the girls promise 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. But when Allie makes an unexpected find at the dig site, the grisly artifact sends her spiraling back in time to a Roman encampment besieged by rampaging Celts. As she struggles to survive in the past, Clare and Milo race desperately against time in the present to bring Allie home ... before she loses her head or her heart.