They began to trot, moving steadily toward the shelter of a stand of trees that had grown up in the center of the strip. As they did, Remi looked back. One of the men had stopped on the hill and was bringing a rifle up to his shoulder. “Sam! Run!”

There was the crack of a bullet as it passed over their heads, and, about a second later, the sound of the rifle shot reached their ears. The next sound was the explosion of the Jeep, a gasoline fireball lighting the evening sky. Sam and Remi were running hard now, weaving to keep the trees and brush between themselves and the men. They had the advantage of a level surface and a clear path, where they could sprint without fear of tripping, while the men on the slope had to move along the hillside at an angle to avoid building up too much speed and tumbling down.

Sam glanced over his shoulder as a second man stopped and shouldered his rifle. “Another one. Take cover!” They both went low and ducked behind a cluster of trees. There was another shot, and the bullet pounded into one of the trees, sending a shower of bark chips in all directions. Sam peered around the trunk and saw the man adjusting his telescopic sight. “Go!”

Sam and Remi ran, working their way up to a full sprint as they approached the high wall surrounding the cenote. They ran around it to the far side and between the two layers of overlapping wall into the entryway. Sam began to pile loose stones in the narrow way to block it while Remi went to their backpacks and retrieved their four pistols, spare magazines, and boxed ammunition. Each of them checked to be sure the guns were loaded.

“I can’t believe this,” Remi said. “Who could they be?”

“Nobody we want to know. They seem to have tracked us, following our trail, then opened fire as soon as they saw us.”

“Who can they think we are?”

“Future dead people.” He put his arm around her and gave her a hug. “Let’s see if we can use this wall to stay alive.”

“I’ll go up to the walkway and see what they’re up to.”

“Keep your head low,” he said.

She pulled her baseball cap lower on her head. “Unfortunately, we’ve been in these situations before.”

“If we live through this one—”

She put her finger on his lips. “Shh. I know, bubble baths and spa treatments. We’ve already made each other all the promises we need.” She took a pair of pistols and climbed to the walk along the top of the wall, found her way to a spot where the wall had crumbled a bit and left a small dip, then rose enough to survey the strip of land the men were approaching.