Straight away, the differences between a traditional labyrinth and her memory of the image carved on the cave wall and ring were obvious. A classical labyrinth was made up of intricately connected concentric circles leading in ever-decreasing circles to the center, whereas she was pretty sure the one in the Pic de Soularac had been a combination of dead ends and straight lines which doubled back on themselves, leading nowhere. It was more like a maze.

The true ancient origins of the labyrinth symbol and mythologies associated with it were complex and difficult to trace. The earliest designs were thought to be more than three thousand years old. Labyrinth symbols had been discovered carved in wood, rock, tile or stone, as well as in woven designs or constructed into the natural environment as turf or garden labyrinths.

The first labyrinths in Europe dated from the late Bronze Age and early Iron Age, from 1200 to 500 B.C., and were discovered around the early trading centers of the Mediterranean. Carvings dated between 900 and 500 B.C. had been found at Val Camonica in northern Italy and Pontevedra in Galicia, and in the top northwestern corner of Spain at Cabo Fisterra Finisterre. Alice looked hard at the illustration. It was more reminiscent of what she’d seen in the cave than anything else so far. She tilted her head to one side. Close, but not a match.

It made sense that the symbol would have traveled from the east with the merchants and traders from Egypt and the outer reaches of the Roman Empire, adapted and changed by its interaction with other cultures. It also made sense that the labyrinth, evidently a pre-Christian symbol, should have been hijacked by the Christian church. Both the Byzantine and the Roman Church were guilty of absorbing much older symbols and myths into their religious orthodoxy.

Several sites were dedicated to the most famous labyrinth of them all: Knossos, on the island of Crete where, according to legend, the mythical Minotaur, half-man, half-bull, had been imprisoned. Alice skipped them, instinct telling her that line of research would take her nowhere. The only point worth noting was that Minoan labyrinthine designs had been excavated at the site of the ancient city of Avaris in Egypt, dating back to 1550 B.C., as well as found in temples at Kom Ombo in Egypt and Seville.

Alice filed the information at the back of her mind.

From the twelfth and thirteenth centuries onward, the labyrinth symbol was appearing regularly in hand-copied medieval manuscripts that circulated around the monasteries and courts of Europe, with scribes embellishing and developing illustrations, creating their own trademark designs.

By the early medieval period, a mathematically perfect eleven-circuit, twelve-wall, four-axis labyrinth had become the most popular form of all. She looked at a reproduction of the carving of a labyrinth on the wall of the thirteenth-century church of St. Pantaleon in Arcera, northern Spain and another, slightly earlier, from the cathedral of Lucca in Tuscany. She clicked on a map showing the occurrence of labyrinths in European churches, chapels and cathedrals.

That’s extraordinary.

Alice could hardly believe her eyes. There were more labyrinths in France than in the whole of Italy, Belgium, Germany, Spain, England and Ireland put together: Amiens, St. Quentin, Arras, St. Omer, Caen and Bayeux in northern France; Poitiers, Orleans, Sens and Auxerre in the center; Toulouse and Mirepoix in the southwest; the list went on and on.

The most famous pavement labyrinth of all was in northern France, set in the center of the nave of the first-and most impressive-of the Gothic medieval cathedrals, Chartres.

Alice smacked her hand on the table, causing several disapproving heads to pop up around her. Of course. How stupid could she be? Chartres was twinned with her hometown of Chichester, on the English south coast. In fact, her first visit abroad had been on a school trip to Chartres when she was eleven. She had vague memories of it raining all the time and standing huddled in a raincoat, cold and damp, beneath imposing stone pillars and vaults. But she had no recollection of the labyrinth.

There was no labyrinth in Chichester Cathedral, but the city was also twinned with Ravenna in Italy. Alice ran her finger across the screen until she’d found what she was looking for. Laid into the marble floor of the church of San Vitale in Ravenna was a labyrinth. According to the caption it was only a quarter of the size of the labyrinth in Chartres and dated to a much earlier period in history, perhaps as far back as the fifth century a.d., but was there all the same.

Alice finished cutting and pasting the text she wanted into a text document and hit Print. Once it was going, she typed “Cathedral Chartres France” into the search box.

Although there had been some sort of structure on the site as far back as the eighth century, she discovered the current cathedral in Chartres dated from the thirteenth century. Ever since then, esoteric beliefs and theories had attached themselves to the building. There were rumors that within its vaulting roof and elaborate stone pillars was concealed a secret of great significance. Despite the strenuous efforts of the Catholic Church, these legends and myths endured.

No one knew on whose orders the labyrinth had been built or for what purpose.

Alice selected the paragraphs she needed, and then exited.

The last page finished printing and the machine fell silent. All around people were beginning to pack up. The sour-faced receptionist caught her eye and tapped her watch.

Alice nodded and gathered her papers, then joined the line at the counter waiting to check out. The queue moved slowly. Shafts of late-afternoon sunlight fell through the high windows in Jacob’s ladders, making the particles of dust dance in the beams.

The woman in front of Alice had an armful of books to check out and seemed to have a query about each one. She let her mind focus on the worry that had been bugging her all afternoon. Was it likely that in all the hundreds of images she’d looked at, in all the hundreds and thousands of words, there hadn’t been a single exact match for the stone labyrinth at the Re de Soularac?

Possible, but not likely.

The man behind her was standing too close, like someone on a tube train trying to read the newspaper over her shoulder. Alice turned and glared at him. He took a step back. His face was vaguely familiar.

“Oui, merci,” she said, as she got to the desk and paid for the printing she’d done. Nearly thirty sheets in all.

As she emerged on to the steps of the library the bells of Saint-Etienne were striking seven. She’d been in there longer than she realized.

Keen to be on her way now, Alice hurried back to where she’d parked the car on the far side of the river. She was so caught up in her thoughts that she didn’t notice the man from the queue following her along the river walkway, keeping a safe distance. And she didn’t notice him take a phone from his pocket and make a call as she pulled out into the slow-moving traffic.