Ned reddened and shrugged, then led Nancy toward a small hut. As they approached it, Nancy noticed a metal box on top of a pole. She saw another one just like it about fifty yards farther along the fence. "What are those things?" she asked.

            "Time-lapse cameras," Ned replied. "They're set to take exposures every fifteen minutes. They even record the date and time at the bottom of each negative."

            "Incredible," Nancy said, then pointed to the hut. "Is that where Brad was hurt?"

            "Yeah," Ned replied. "We keep a few snacks and drinks in there. Apparently, Brad was heating water for coffee. When boom! I heard the explosion and ran up the hill. Brad was lying across the doorstep, unconscious."

            Nancy shook her head sympathetically. "The force of the explosion must have blown him out the door. He's lucky he wasn't killed."

            Inside the hut were two chairs and a folding table covered with computer printouts and camera gear. Several bags of food pellets and a stack of traps lined the far wall. Above it was a shelf with a canister of sugar, instant coffee, and tea bags.

            Nancy pointed to a blackened object in the comer of the room. "Is that the stove that blew up?"

            Ned nodded, and she went over to it. The stove consisted of one burner attached by a copper tube to a canister of propane. Nancy checked the propane tank. The fitting between it and the tubing was tight, but when she traced a path up the tubing to the nut that connected it to the burner, she let out a gasp.

            "Find something?" Ned asked.

            Nancy held the tubing and the bolt up to the light. "Look at this," she said. "See those scratch marks? Someone's tampered with the nut,"

            Ned's eyes narrowed. "That means when Brad turned on the stove, propane started escaping."