Vaill took the flash and trained it on the outline of a two-by-two square cut into the wood of the floor. There were two hinges on one side and a rusting metal ring in the center of the other.

“Bingo is right, brother,” he said. “Any doubt as to where that trapdoor leads?”

Lou pumped his fist.

“None,” he said. “Absolutely none. All we got to do now is get in there.”

The unadorned door to the stone house, probably steel, was facing south. Without being told, Lou unholstered his Glock, stepped back two paces, and discharged three well-aimed rounds into the keyhole, each sending out a small burst of sparks. The rippling echo of gunfire rolled away like a cresting wave. Vaill inspected the keyhole, tested the thick metal handle, and shook his head. Then he removed his backpack and opened it up.

“Time to sic the Doberman on it,” he said. “His Christian name is C-4, but he’ll answer to almost anything. Stand by, my friend.”

Lou knew very little about plastic explosives. Obviously, it was a moldable material, but he had little knowledge of the chemistry that made it work. Vaill took a wedge of the whitish putty from a tinfoil wrapper, and shaped it in and around the keyhole and along the hinges.

“As with most decent explosives,” Vaill said, “serious energy is needed to initiate the chemical reaction. That’s what these blasting caps are all about.” He inserted one into each lump of putty, and rolled out enough detonator wire for them to get a safe distance away. “You can shoot bullets into C-4 all day and it won’t go off,” he went on. “Put a match to it and it’ll just burn slowly. What we need is a smaller explosion to trigger a bigger one.”

Vaill held up a black metal box about the size of a deck of cards—the detonator. He flicked a switch and a green light came on. Then he attached the three wires to a spool. His thumb hovered over the red button on top of the box.

“Ready?” he asked.

“Are we far enough away?”

“We’re about to find out. Move behind that tree and hold your ears, pal.”

Lou shrugged and did as asked, and his partner depressed the button. The three simultaneous blasts were more intense than Lou would have ever anticipated given the size of the explosives. Even behind the tree, the shock drove him back a foot and seemed as if it momentarily stopped his heart. Debris shot out in all directions. Lou peered out as the wall of smoke quickly dissipated. Astonishingly, the door was still standing.

“What happened?” Lou asked, stunned.