In the other direction, however, was a machine gun on a tripod. It had a square body with a long barrel that ended in a sort of flare. Around the barrel was a perforated metal sleeve, the air-cooling jacket. They stared at the gun for a moment, half expecting it to open fire.

Gunther motioned them back to the safety of the tunnel from which they had come. Seth peered around the corner as Gunther walked up to the machine gun and swiveled it toward the bright white salt wall. Next, he took a pair of wire cutters and clipped the tripwire. It fell slack in the middle of the tunnel intersection.

Gunther started to walk back toward them, then stopped and went back to the machine gun. He bent over the gun and pulled the trigger.

The gun leaped to life, filling the tunnels with fire and noise for perhaps a dozen rounds, and then fell silent as the hammer fell on a dud.

A smell that reeked of cordite and the ghosts of ancient enemies come to life accompanied Gunther back to where the group had gathered.

“That’s why we must be careful,” he said, then ordered the tape brought up and planted firmly at the edge of the intersecting corridor. He then took the other end and began walking again. As he got to the intervals indicated on the plans, he would turn one way or another to circumvent the mines.

A hundred yards on, he bent to rip the camouflage from a deep pit. A clattering of boards filled the mine, accompanied by a rolling cloud of dust as the materials dropped into the hole. Like the others, Zoe shone her light into the pit as she walked the narrow ledge between it and the tunnel wall. Barbed metal spikes that looked to be three feet long grinned back up at her.

The mines grew closer together, and the number of booby traps they had to disarm increased as they neared the chamber containing the shroud’s vault

Their first surprise came as they stepped into a huge chamber nearly as large as the auditorium-sized one in the other mine. They had moved inch by inch, skirting a field of mines that had been placed side by side, with barely room for a footprint between the triggers. Gunther took a can of the carbon black from Zoe and sprinkled it, not in a path, but in the specific places where they should put their feet. Placement had to be precise. To slip or lose one’s balance could mean being ripped apart by the explosives buried beneath the salt.

This last minefield was nearly forty feet wide. Gunther had them all wait nearly fifty yards behind as he picked his way through the mines. In the dimly lit distance, he seemed to move at a stop-frame pace.

They all stood silently, holding their breaths. Zoe looked at Father Morgen and saw his lips moving in a silent prayer.