“And, of course, subsequently, the Virgin Mary.” Lucy had been thinking about this in relation to what she had absorbed from the guidebook for Chartres. “These other cathedrals—Reims, Bayeux, and Amiens—all had labyrinths, though only Chartres has had its original intact since 1200.” She was fascinated, and thought of the palm cross in the Bible at the house. “It’s interesting that the Virgo figure holds the palm leaf, and you were christened on Palm Sunday, Alex. What about this star—Alpha, you said—which is at the bottom of the tail? Could that be the house in L’Aigle?”

Alex looked at her. “It’s an interesting idea. ‘My alpha and my omega.’ Do you feel it’s related to Will’s central document?”

Lucy smiled at him. “It could be, if whatever was in the garden is both the alpha star of Virgo and the omega of the clues—beginning and end.”

Alex suddenly felt uncomfortable. “Dad, you don’t believe all this sacred geometry means anything, do you?”

Henry took a moment. “What’s important, Alex, is not whether there is actually any truth in it. There may be, who knows? But what’s interesting is that the Gothic architects believed it. It does seem to have been constructed this way—whether you accept there’s anything supernatural about it or not. The overlay of Christianity on the site of some presumably older female shrine would have excited your mother. She loved that woven feel—the way one deep myth was the background of another. The plurality of faiths, she called it. She would have found it heartening that they had embraced rather than eradicated the old core rituals. She felt it gave continuity to the shape of human belief—that it showed how there was one common thread behind such a variety of religions. Virgo’s connection with the Virgin Mary would have delighted her.”

“There’s something written on the back of the frame,” Grace alerted them.

Turning it over, Lucy read: “‘She is both sister and bride.’” She spoke with animation. “And your mum obviously attached some significance to it, Alex. She made this tapestry, created that garden. Something was in her head. And Will must have started to decipher it too, don’t you think?”

At this point Alex looked at the intrigued faces in the room and softly asked Lucy: “Would you show my father what we found in the garden?”

She produced the tile, inverted it carefully to reveal the strange star-shaped pattern with its motto below, and the key taped teasingly in the center. “Whatever was there, Will found it first. This has to be connected with his bike, doesn’t it?” Lucy asked him.