When their home in Cape Verde is attacked and burned by Sir Francis Drake in the 16th century, Tontorix and Diaecus decide to travel on a galleon to explore the New World. Upon arriving in colonial Brazil, the two ancient Celts build a new home for themselves, but are forced to flee when the Dutch arrive to attack and occupy Portuguese settlements. They escape into the wilderness and take up residence in Palmares, a community of runaway slaves who are continuously hunted by the Europeans looking to re-enslave them.

As the centuries pass, they encounter and adapt to new technologies and scientific discoveries that greatly alter the world around them.

In the 19th century, they embark on a mission to bring two murderers to justice for a large bounty, and their relentless pursuit of the outlaws takes them across the vast and beautiful North American frontier. Years later, when everything they hold dear is threatened, they are forced into a final and epic conflict.