The Evening and the Morning by Ken Follett
It is 997 CE, the end of the Dark Ages. England is facing attacks from the Welsh in the west and the Vikings in the east. Those in power bend justice according to their will, regardless of ordinary people and often in conflict with the king. Without a clear rule of law, chaos reigns.
In these turbulent times, three characters find their lives intertwined. A young boatbuilder's life is turned upside down when the only home he's ever known is raided by Vikings, forcing him and his family to move and start their lives anew in a small hamlet where he does not fit in. . . . A Norman noblewoman marries for love, following her husband across the sea to a new land, but the customs of her husband's homeland are shockingly different, and as she begins to realize that everyone around her is engaged in a constant, brutal battle for power, it becomes clear that a single misstep could be catastrophic. . . . A monk dreams of transforming his humble abbey into a center of learning that will be admired throughout Europe. And each in turn comes into dangerous conflict with a clever and ruthless bishop who will do anything to increase his wealth and power.