Zoe said a silent prayer.

In a minute the rocks had stopped falling, and once again they were alone in the tunnel with the sounds of their own breathing. Gunther hesitated for several more seconds, then moved forward without talking.

Over and over in his mind, Seth ticked off the things they would have to deal with once they crossed over into the Habersam mine. They had gone over the plans and the instructions from the safe deposit box half a dozen times. The Nazi maps of the mine marked with the locations of the planted explosives and other devices were compared with the mine company maps Gunther had been able to obtain locally.

Not surprisingly, the two maps were not in total agreement. The mining company maps showed tunnels where the Nazi map showed none. Just as cartographers—before the days of aerial and satellite mapping—used to differ on the shapes of the continents, mining engineers of forty years past used comparatively crude methods, a fact that guaranteed that no two mining maps, particularly those of small backwoods mines, would be the same.

Today, though, even minor differences could prove to be dangerous, since it was necessary to know exactly where the Nazi traps were located. A foot the wrong way, or even a few inches, could mean disaster.

“And of course we have no way of knowing if everything is properly charted,” Gunther had told them the night before. “The commandant of the SS unit could have ordered other protective measures in the last days of the war and not bothered to update the materials in the box.”

The ice in the tunnel gradually thawed as they walked deeper into the mine. Filling the tunnel now was the sound of running water.

“The hills are riddled with underground streams and rivers,” Gunther had said. “The greatest danger that a miner faces, next to cave-ins, of course, is the disaster that results from blasting through a rock wall only to find an underground stream.”

He explained that rain and melting snow seeped into water—re-taming layers of rock, which gradually migrated downward. Some of it flowed naturally into fresh water springs that fed mountain streams. But much of it ran along the cracks and fissures in the rock of the mountains, and eventually into the ubicpiitous salt deposits buried underneath. The salt, some of it containing sulfur and other minerals, dissolved in the water and was carried down with it toward the warmer layers of rock that lay at the base of the mountains. Eventually, many of these warm, mineral-laden streams of water emerged at the surface again, in the guise of the warm mineral springs around which the great spas were built.

Seth recalled Gunther’s words now as he walked through the tunnel the walls of rock on either side seeming to press malevolently inward, reaching out for him as if they wanted his life. He had an urge to walk faster, but Gunther set the pace. Seth tried to pass off his anxiety as mild claustrophobia. The real danger lay ahead.