Young Simon was walking happily beside him, his father on the other side. So far, no sign of danger.

The ceremony was being held under a magnificent awning on the parvis of Notre Dame, just in front of the cathedral’s great west doors. There the king’s little sister was going to marry her kinsman, Henry of Bourbon, King of Navarre.

In a way, it was a dynastic marriage—perhaps a necessary one—for her family and for France. For although her two brothers were living, they had no male children as yet. In another generation, the Valois line of the ancient Capet royal family would die out. And who was next in line? Quite a distant cousin, as it happened. The Bourbon line descended directly from a younger son of that saintly King Louis who’d built the Sainte-Chapelle two centuries ago. The bridegroom’s father had married the queen of the little mountain kingdom of Navarre that lay between France and Spain in the Pyrenees, of which his son Henry was now king. So if Henry of Navarre did inherit the throne of France, the Bourbon and Valois lines would be conveniently joined again.

But despite the dynastic convenience, this marriage provoked one, very big question.

“Cousin Guy,” Simon now demanded, “why is the Princess of France marrying a Protestant?”

It was amazing really, Guy considered. Fifty years ago an obscure monk named Luther had challenged the Catholic Church, and because of it the whole of Western Christendom was now divided into two armed camps. To the north and east, the Netherlands, many of the German principalities and much of Scandinavia was in the Protestant camp. England was too. The pope had just excommunicated the heretic Queen Elizabeth, and invited good Catholic rulers to depose her. Spain, meanwhile, and the Holy Roman Empire of central Europe were in the hands of the most Catholic Hapsburg dynasty.

And France? The humanist King François had tolerated Protestants in his realm for a while. By the time he’d decided they were dangerous, it was too late. The north of France was solidly Catholic. So mostly was Paris. The modest numbers of Protestants in the city worshipped quietly, in their own houses mostly, and took care not to draw attention to themselves. But in the southern mountains and Atlantic ports like La Rochelle, huge numbers of people had taken the new faith. They went by many names—Protestants, Reformers, Calvinists, Huguenots. Many were humble craftsmen, but others were merchants and knights. Admiral Coligny, the finest military commander in France, had gone over to the new faith. And the mother of Henry of Navarre had also converted, and taken her family with her.

The Protestants had demanded freedom of worship. The royal government had clamped down. There had been a succession of regional conflicts and truces.

“You know,” Guy said to young Simon, “that there has been fighting with the Protestants in recent years? Not here in Paris, thank God, but in other places.”