The rumble echoed across the reservoir.

“What was that?” Dirk Pitt raised his head from behind a pair of computer monitors where he’d been watching a sonar image of the lakebed. He peered across the cramped wheelhouse of the workboat at the short burly man piloting the vessel.

“It wasn’t thunder.” Al Giordino glanced out the side window at blue skies. “Or my stomach, despite our meager excuse for lunch.” He crumpled a potato chip bag and tossed it onto the dash, then shifted his gaze out the windscreen.

He suddenly sat upright. “Oh, brother, take a look at that. It’s the dam.”

Pitt stood, stretching his six-foot three-inch frame, and looked off the bow. Less than a quarter mile ahead, the rim of the Cerrón Grande Dam stretched across the reservoir. But now the structure had a huge gap at its center. Two small boats were just in front of the opening, being drawn into the void.

“The dam’s given way,” he said, “and those boats are going with it.”

Giordino jammed the throttle forward. The thirty-foot workboat surged ahead, driven by a twin set of 250-horsepower outboards. Rather than turn away from the danger, he aimed straight for the havoc.

He glanced over his shoulder across the open stern deck to a taut blue cable that trailed in the frothy wake behind them. A hundred meters back, a yellow sonar towfish broke the surface and bounded through the water.

“No time to reel it in,” Pitt said, reading Giordino’s thoughts. He stepped to the rear cabin door. “Get as close as you can.”

Pitt stepped onto the open deck, retrieved a life ring from the bulkhead, and tied it to a coil of line stored in a bucket. He moved to the transom and tied off the free end to a stern cleat. Looking over the side toward the dam, he wondered if they would get there too late.

* * *

• • •

ELISE DIDN’T NOTICE the survey boat charging toward them. She focused on the old fisherman in the nearby canoe, fighting for his life. Despite his fierce attempt to paddle clear, the narrow wooden craft was quickly being drawn backward toward the cascading torrent. The old man’s skinny arms flailed with hard, even strokes, but he was powerless against the gushing force.

“Rondi, can you help him?”

She had to yell over the roar of the falling water. The teen winced, then adjusted the tiller, angling the boat toward the fisherman’s path.

Elise slipped the satchel over her neck, then grabbed the side of the canoe and pulled the two boats together. The fisherman nodded thanks—and continued to slap the water on the opposite side with his paddle.

It was a losing battle. Both boats were sliding toward the abyss, now less than a hundred feet away.

Above the din of the waterfall, Elise noticed a new sound: the whine of large engines. The survey bo

at was charging toward the dam at top speed.

The boat curled around in a wide arc, trailing a blue cable, then slowed as it pulled just in front of them. A tall man with black hair standing at the stern tossed them a line.

“Tie off one of the boats,” he yelled. “We’ll pull you clear.”

The rope landed on the aluminum boat’s bow, and the fisherman grabbed it. Rather than tie it to one of the boats, he wrapped it around his waist and jumped into the water.

Elise couldn’t believe her eyes. She glanced back and saw the plunging water was less than fifty feet away. The draw of the falls was getting stronger, even as Elise let go of the canoe.

But the survey boat was following their position, its pilot feathering the twin outboards to stay near. On the stern, the tall man furiously pulled on the rope until the fisherman’s head bobbed alongside. He yanked the old man from the water and freed him from the line. Gathering the rope together, he again tossed the line toward the boat.

“Tie it off,” he shouted.

As the line flew through the air, the aluminum boat pivoted in the accelerating current. The line went high and to the side, but Rondi grabbed for it anyway. “I’ve got it.” He stood and stretched over the side.

A few feet ahead of him, Elise attempted a similar move. With both their weights shifted to the starboard rail, the boat dipped to the side, and the top of the gunnel kissed the water.

Elise tried to jump back. It was too late. The water poured in, flooding the interior, capsizing the boat.

Elise instinctively grabbed onto the boat, but it pulled her under as it sank. She let go and flailed to the surface. Gulping for air, she glimpsed Rondi rushing by, clinging to the line. With a flash of terror, she realized it was he who was stationary. She was the one speeding through the water.

With renewed panic, her heart pounding, she tried swimming away from the dam. The swift current drained her strength as she heard and felt the rumble of the falls closing in behind her.