"Include yourself, Sheriff. They must have known you and your men would have accompanied us back to Dr. Ambrose."
"Where is the professor?" wondered Marquez aloud. "Where did he and the killer go?"
"There are two possibilities," said Pitt. "The first is that the killer regained consciousness, overpowered Doc Ambrose, killed him and dumped his body down the nearest mine shaft. Then he placed the charge and escaped through another tunnel leading to the outside."
"You should write fairy tales," said Eagan.
"Then explain the booby trap."
"How do I know you didn't set it?"
"I have no motive."
"Get off it, Jim," said Marquez. "Mr. Pitt hasn't been out of my sight for the past five hours. He just saved our lives. If the blast didn't get us, the cave-in w
ould."
"We're not certain the bundle contains explosives," Eagan said stubbornly.
"Then trip the wire and see what happens." Pitt grinned. "I, for one, am not going to hang around and find out. I'm out of here." He rose to his feet and began strolling along the ore car tracks back to the hotel.
"One moment, Mr. Pitt. I'm not through with you."
Pitt paused and turned. "What are your intentions, Sheriff?"
"Check out the sack wired to the timber, and if it's an explosive device, disarm it."
Pitt took a few steps back, his face dead serious. "I wouldn't if I were you. That's not some bomb built in the backyard of a junior terrorist. I'll bet my next paycheck it was exactingly assembled by experts and will burst at the slightest touch."
Eagan looked at him. "If you have a better idea, I'd like to hear it."
"The ore car sitting a couple of hundred yards up the track," replied Pitt. "We give it a shove and let it roll through here and trip the wire and detonate the explosives."
"The roof of the tunnel will collapse," said Marquez, "blocking it forever."
Pitt shrugged. "It's not like we're destroying the tunnel to deny access to future generations. We're the first to have passed through this section of the mine since the nineteen-thirties."
"Makes sense," Eagan finally agreed. "We can't leave explosives laying about for the next underground explorers who walk through here."
Fifteen minutes later, Pitt, Eagan, Marquez, and the deputy had pushed the ore car to within fifty yards of the trip wire. The heavy iron wheels squeaked and protested for the first fifty feet, but soon loosened and began to roll smoothly over the rusty rails as the ancient grease on their axles lubricated the roller bearings. The four sweating men finally reached the crest of a slight slope that led downward.
"The end of the line," Pitt announced. "One good shove and she should roll for a mile."
"Or until she drops into the next shaft," said Marquez.
The men heaved in unison and ran with the car, propelling it until it picked up speed and began to outrace them. They staggered to a halt and caught their breath, allowing their pounding hearts to slow.
Then they held their flashlights on the ore car as it charged over the rails and disappeared around a gradual curve of the tunnel.
Less than a minute later, a tremendous detonation tore through the tunnel. The shock wave nearly knocked them off their feet. Then came a cloud of dust that swirled around and past them, followed by the deep rumble of tons of rock falling from the roof of the tunnel.
The rumble was still ringing in their ears, the echoes reverberating in the old mine, when Marquez shouted to Eagan, "That should stifle any doubts."
"In your haste to prove your point, you overlooked something," Eagan said loudly, his tone dry and provocative.
Pitt looked at him. "Which is?"
"Dr. Ambrose. He could still be alive somewhere beyond the cave-in. And even if he's dead, there will be no way of retrieving his body."