On the run across America from a vengeful shape-shifter, Bannerman Bann Boru has only one thing on his mind: keeping himself and his young son, Cor, alive. At any cost.

Then he meets Shay Doyle, healer and member of a secret group of immortal Celtic warriors, the Tuatha De Danaan, who live in modern-day Colorado. When Cor is injured, Bannerman is forced to accept her help. He quickly realizes that the golden-haired healer is shield-maiden tough and can hold her own on the field of battle with the big boys. And Shay soon discovers that there is more to Bann then meets the eye.

Now, with the shape-shifter Cernunnos teaming up with the local pack of Fir Bolgs (Bronze Age creatures with a nasty taste for children), Bannerman, Shay, her wolf-dog Max, and the rest of the Doyle clan must figure out how to battle one insane god.