The old lime mortar gave way surprisingly quickly and he loosened the bricks, holding on to them to kill the sound, placing them quietly on the plastic sheeting. Through the aperture he had made he could see what looked like a beautifully constructed hiding space, set into the thick wall behind the bricks. It might have been part of the fireplace, or a priest’s hole from centuries lost. Prying into the hole once more, with the help of the flashlight, he beckoned to his accomplice to join him. Among the piles of dust and cobwebs they saw two aging boxes—the larger square and bound with an elaborately tied rope, and the other with a curved, gold-topped lid bearing a painted inscription.

They now hastened to clear the remaining bricks and haul the boxes into the open area behind the shelves. They gave their immediate attention to the smaller of the two. An exploratory tug proved that it was locked fast, but an elaborate keyhole in each side was revealed in the laser light. One gloved hand streaked away some dust to reveal the words of the inscription. Their heads consulted each other, hesitating; then cautiously they pushed this box aside and concentrated on the larger one. The knot in the cord was stiff and complex, and after a moment’s struggle, the taller of the two was handed the knife by his associate. He paused fleetingly, then sliced cleanly through the cord.

Inside the box was a large parchment covered with complex mechanical drawings and notes. Underneath this was a collection of what appeared to be crude, scientific equipment: an odd selection of tarnished brass tubes, some clamps, mirrors, and a prism-shaped piece of what the focused flashlight revealed to be fine clear crystal. Separately wrapped in fragile cloth was an extraordinarily detailed set of lines and shapes etched or drawn onto a piece of glass.

The visitors removed the contents from the box and spread them out carefully on the floor, studying them. Eventually one man spoke, almost the only words uttered within the confines of the shop: “Non angli, sed angeli,” and he muffled a laugh. Both men nodded, then carefully rolled the paper, wrapped the glass painting back into its cloth, and replaced both objects in their original coffer along with the other pieces of equipment. One man blew through a straw or small pipe, scattering a tilth of dust again on top of the smaller, untried box. After some moments, they returned this one alone to its original hiding place, keeping the second close by them.