As I watched Alafair dive off our rented boat, just the other side of Seven-Mile Reef, her tan body glazed with sunlight and saltwater, I thought of children everywhere, and I thought of the pain that can be inflicted on them like a stone bruise in the soul, like a convoluted, blood-red rose pushed deep into the tissue by a brutal thumb.

She floated above the reef, watching the schools of clown fish and mackerel, blowing saltwater out her snorkel, the small waves lapping across her back and thighs. Thirty feet below, the sand was like ground diamonds; you could see each black spike in the nests of sea urchins, and the fire coral was so bright it looked as if it would scorch your hand with the intensity of a hot stove.

Then I saw a long, tubular shadow ripple across the crown of the reef and flatten out on the ocean floor. It must have been eight feet long. A floating island of kelp obscured my angle of vision, then the shadow changed directions and I saw the glistening brown back of a hammerhead shark.

When he turned and flipped his tail fin I could see one round, flat, glassy eye, his gash of a mouth, the jagged row of razor teeth, the obscene pale whiteness of his stomach.

I yelled at Alafair, but her ears were half underwater and she didn't hear me. I kicked off my canvas shoes, stepped up on the gunwale, hit the water in a long, flat dive, and reached her in three strokes. By now she had seen the shark, and her face was terrified when I grabbed her around the waist and began swimming back to the boat. Then a peculiar thing happened. She knew that we were fighting against each other, that our legs were thrashing impotently in a shimmering cone of wet light above the shark's murderous gaze, and I saw a quiet, almost naive expression of resolution replace the fear in her face. She worked the mask and snorkel off her head, hooked them on her arm, and began to swim with me toward the boat ladder, her body horizontal, her head twisting from side to side so she could breathe above the chop.

I pushed her rump over the gunwale, then toppled over it myself onto the deck. I hugged her against me on the hot boards, and pressed her head tightly under my chin.

She looked up at me, and I saw concern coming back into her face.

"Wow!" I said, and tried to grin.

"What kind of shark was that, Dave?"

"It was a nurse shark. They're big wimps. But who wants to take any chances?"

"His head… it was ugly. It looked like he'd eaten a big brick." Then she smiled at her own joke.

"Those nurse sharks are not only wimps, they're dumb wimps. They're always swimming into the sides of boats and reefs and things," I said.

Her brown eyes were happy and full of light again.

"Hey, Dave, we gonna put out the lines and troll for mackerel?"

"Sure, little guy," I said, and squeezed her against my chest again, my eyes tightly shut, hoping that she would not feel the fearful beating of my heart.