Dave shook his hand. “Thanks, Sam. That’s really thoughtful.”

As soon as Sam and Remi were alone she said, “No theories, Sam? Really? How about the people in the black-and-gray boat who have been stalking us for days?”

“I didn’t say no, I just shrugged.”

“If something else happens, don’t you want them on the sergeant’s record?”

“Well, if something happened to make those people upset, I’d find it inconvenient to have it in the police record that I suspected them of doing us harm.”

“I see,” she said. “This should be an interesting day.”

Sam moved around the boat, taking an inventory of equipment, before casting off the lines. Remi started the engine and drove slowly out of the marina toward the Gulf. The world ahead was all deep blue sky and sea that met at the horizon and seemed to go on forever.

Sam stood beside her as she came around the breakwater and added speed. “I’m hoping to get this site finished today so that before we move on to the next site we can feel we’ve got everything there is to find.”

“Fine,” she said. “That sounds like a peaceful ambition.”

They moved westward along the flat green Louisiana coast toward the spot where they’d been diving. But as they came closer Remi said, “You might want to look ahead.”

Sam looked over the cabin roof into the distance. He could see the black-and-gray boat anchored ahead. The red-and-white flag was up, and there were people in the water. “Interesting coincidence,” he said. “Our diving gear gets sabotaged and now we find these people diving in our exact location.” Sam took out the binoculars and stared in the direction of the black-and-gray boat for a few seconds. “They seem to be getting out of the water. Now they’re pulling in their dive buoys and striking the flag.”

“Well, of course,” said Remi. “The famous treasure-hunting Fargos, it turns out, have been diving for broken pottery and deer antlers. Now these people have figured that out.” She slowed the engine. “Let’s let them get out of here. I’m not going down sixty feet and leaving them up here with our boat.”

“Maybe that’s not why they’re leaving. If we can see them, they can see us. Let’s try another approach. Keep an eye on them for a minute.” He went into the cabin and returned with a chart. He held it up where Remi could see it. “Head along here toward Vermilion Lake. When we get there, I’d like you to take a winding course up into the bayou.”

“That’s a little vague.”

“I don’t want to stifle your creativity. Let’s see if you can lose them.”

Remi started to move forward, set herself on the proper compass course, and gradually pushed the throttle up, making the 427 Chevrolet engine roar. She shot past the black-and-gray boat at a distance, and kept going at the same speed. After a few minutes, Sam tapped her on the shoulder and she looked back. When she saw the black-and-gray boat coming after them at high speed, she threw her head back and laughed. “Not very subtle, are they? I guess it’s a race.” She pushed the throttle forward all the way, then tapped it with the heel of her hand to get the last bit of speed out of it. As she sped west along the Caminada Headland, she looked delighted.

Now and then the boat would reach a freak wave and leap over it. Remi would flex her knees to take the jump like a skier, cling to the steering wheel, and then duck to avoid the splash that the wind sent back at them. Sam stood close to her and said, “You can slow down a little bit now. If they lose sight of us this early, they might give up. We want them fully committed.”

“Aye, aye,” she said.

She drove on, keeping their pursuers barely in sight, until Sam said, “All right. Now go into Vermilion Lake.”

She turned right, sped across the open water, and then headed for the bayous. As she shot into the first narrow, winding channel, she gradually pulled back the throttle. “Hey, make yourself useful,” she said. “Get up to the bow and make sure I don’t hit anything that’s alive or puts holes in boats.”

“Happy to,” Sam said. He got up on the foredeck and pointed in the direction that was clearest. He studied the water for snags and shallow spots and kept her out of them. The water was dark and nearly opaque, the channel lined with reeds and trees hung with Spanish moss and vines. As they moved farther inland, the vegetation grew thicker, and the trees came together to form arches over the water. After a time, Sam called, “Idle the engine.”

The engine went to neutral, and the boat coasted a few yards with a minimum of sound, then stopped and drifted into a shaded copse. Somewhere in the distance behind them they could hear the growl of the black-and-gray boat’s engine. Sam and Remi exchanged a nod, and then Remi sped up again. They went on for another twenty minutes, and Sam waved at her again. She slowed down to a crawl while Sam came aft and looked at the chart.

“Get ready to anchor.”

“Are you sure?”

“Something wrong with this spot?”

“It’s a sweltering, mosquito-infested swamp where the alligators and the rare and celebrated American crocodiles can barely fight off the water moccasins. And I just saw an egret fall out of his tree from heat exhaustion.”

“Perfect,” Sam said. “Let’s get our wet suits on. They’ll protect us from the mosquitoes. Wear your booties, because we’ll be walking. And we might as well bring flippers too, in case we need speed.” Sam studied the chart, then put a big red X in a location about a half mile from their position.

“Isn’t that a little heavy-handed?”

“They will have worked so hard to see it that they’ll need to believe it.”

When they were ready, Sam used the blunt end of the gaff to pole them to shore and used the hook end to hold the boat while they got out and took a few steps into the mud. Sam pushed the boat so it could drift out into the middle of the channel.

“Now what?” she asked.

“Now we go on a great big hike.”

“Charming. Lead on.” She walked along behind him through the reeds and muck.

Every so often Sam would turn back to check on her. She was stepping along at a steady pace, and her face was set in a quiet smile. After about twenty minutes of walking, Sam stopped. “You figured it out, didn’t you?”

“Maybe.”

“Why only ‘maybe’?”

“Are you assuming they put a GPS tracker on our boat?”

He grinned. “I found it. I wondered why they didn’t sabotage the engine, then realized it was so we wouldn’t spend a lot of time looking around in the engine compartment.”

“Then yes. I have figured it out. Let’s finish the trek and see if they’re out following our trail to the treasure.”

He said, “Sometimes you amaze me.”

“Really?” she asked. “Still?”

He led Remi deeper into the swamp and then along a wide right turn so they completed a vast circle. When they came back to their boat, she went a hundred yards up to the next bend and pointed. The black-and-gray boat was anchored up there to hide it from them.

Sam sat down on an old fallen tree trunk, put on his flippers, and pulled his mask down over his face.

Remi put her hand on his arm. “The alligators weren’t just a figure of speech, you know.”

“Don’t tell them I’m here.” He moved into the murky water and disappeared. He reappeared at the stern of the black-and-gray boat. He went to the bow, pulled up the anchor, and let the boat begin to drift downstream.

Remi moved quickly along the shallows to where they had left the dive boat, close to the shore among the dead trees. She used the gaff to push off, lifted the anchor, and looked up the watery channel at Sam, drifting slowly toward her in the black-and-gray boat. She could see he was working with a set of wires he had cut and stripped with his dive knife.

As Remi watched, Sam touched the two wires together, the engine started, and he began to steer the boat down the bayou toward her. She started the engine of their boat and moved along the bayou ahead of him at quarter speed, relying on her memory of where sunken logs and muddy bars had been. In a few minutes she was out into Mud Lake, then into Vermilion Lake, and then out into the Gulf. In a moment, Sam was coming up behind in the black-and-gray boat.