I pointed out to sea. “He must have a boat out there. One of those.”

We saw Shafer striding into the low waves of the Caribbean, heading into a cone of light made by the moon.

He did a shallow dive and started to swim in a smooth-looking crawl stroke.

Sampson and I were down to our underwear, nothing very pretty. We both made shallow dives into the sea.

Shafer was a very strong swimmer and was already pulling ahead of us. He swam with his face in the water, lifting it out sideways after several strokes to catch a breath.

His blond hair was slicked back and shone in the moonlight. One of the boats bobbing out there had to be his. But which one?

I kept a single thought in my head: stretch and kick, stretch and kick. I felt as if I were gathering strength from somewhere inside. I had to catch Shafer — I had to know the truth about what he’d done to Christine.

Stretch and kick, stretch and kick.

Sampson was laboring behind me, and then he started to fall even farther back.

“Go,” I called to him. “Go back for help. I’ll be all right. Get somebody out there to check those boats.”

“He swims like a fish,” Sampson shouted back.

“Go. I’ll be fine. Hold my own.”

Up ahead I could still see Shafer’s head and the tops of his shoulders glistening in the creamy white moonlight. He was stroking evenly, powerfully.

I kept going, never looking back to shore, not wanting to know how far I had come already. I refused to be tired, to give up, to lose.

I swam harder, trying to gain some sea on Shafer. The boats were still a good way away. He was still going strong, though. No sign of tiring.

I played a mind game of my own. I stopped looking to see where he was. I concentrated only on my own stroke. There was nothing but the stroke; the stroke was the whole universe.

My body was feeling more in sync with the water, and I was buoyed as it got deeper. My stroke was getting stronger and smoother.

I finally looked. He was starting to struggle. Or maybe that was just what I wanted to see. Anyway, it gave me a second wind, added strength.

What if I actually caught him out here? Then what? We’d fight to the death?

I couldn’t let him get to his boat before me. He’d have guns on board. I needed to beat him there. I had to win this time. Which boat was his?

I swam harder. I told myself that I was in good shape, too. And I was. I’d been to the gym every day for almost a year — ever since Christine disappeared.

I looked up again and was shocked at what I saw.