When archaeologist Aaron Keeler finds himself transported eighteen years backward in time, he becomes swept up in a strangely illicit liaison with his younger wife. A brilliant musician, Violet is captivated by the attentive, "weathered" version of her husband. The Aaron she recently married--an American expat--has become distant, absorbed by his excavation of a prehistoric site at Kilmartin Glen on Scotland's west coast, where he will soon make the discovery that launches his career. As Aaron travels back and forth across the span of nearly two decades, with time passing in both worlds, he faces a threat to his revelatory dig, a crisis with the older Violet--mother of his two young children--and a sudden deterioration of his health. Meanwhile, Violet's musical performances take on a resonance related to the secrets the two are uncovering in both time frames. With their children and Aaron's lives at risk, he and Violet try to repair the damage before it's too late.