He climbed topside, stretching his tall frame. He wore only a pair of white Quicksilver trunks and a loose shirt, unbuttoned. Employed as a boat mechanic in Darwin Harbor, he and Susan had met during one of the dry-dock repairs on another of the University of Sydney’s boats. That had been eight years ago. Just three days ago, they had celebrated their fifth anniversary aboard the yacht, moored a hundred nautical miles off Kiritimati Atoll, better known as Christmas Island.

He passed her a bottle. “Any luck with the soundings?”

She took a long pull on the beer, appreciating the moisture. Sucking on a salty mouthpiece all afternoon had turned her mouth pasty. “Not so far. Still can’t find a source for the beachings.”

Ten days ago eighty dolphins, Tursiops aduncus, an Indian Ocean species, had beached themselves along the coast of Java. Her research study centered on the long-term effects of sonar interference on cetacean species, the source of many suicidal beachings in the past. She usually had a team of research assistants with her, a mix of postgrads and undergrads, but the trip up here had been for a vacation with her old mentor. It was pure happenstance that such a massive beaching occurred in the region — hence the protracted stay here.

“Could it be something other than man-made sonar?” Applegate pondered, drawing circles with his fingertip in the condensation on his beer bottle. “Microquakes are constantly rattling the region. Perhaps a deep-sea subduction quake struck the right tonal note to drive them into a suicidal panic.”

“There was that bonzer quake a few months back,” her husband said. He settled into a lounge beside the professor and patted the seat for her to sit with him. “Maybe some aftershocks?”

Susan couldn’t argue against their assessments. Between the series of deadly quakes over the past two years and the major tsunami in the area, the seabed was greatly disturbed. It was enough to spook anyone. But she wasn’t convinced. Something else was happening. The reef below was oddly deserted. What little life was down there seemed to have retreated into rocky niches, shells, and sandy holes. It was almost as if the sea life here was holding its breath.

Maybe the sensitive creatures were responding to microquakes.

She frowned and joined her husband. She would radio over to Christmas Island to see if they’d picked up any unusual seismic activity. Until then, she had news that would definitely get her husband in the water in the morning.

“I did find what looked like the remnants of an old wreck.”

“No bloody way.” He sat up straighter. Back at Darwin Harbor, Gregg offered tours of sunken WWII warships that littered the seas around the northern coast of Australia. He had an avid interest in such discoveries. “Where?”

She pointed absently behind her, beyond the yacht’s far side. “About a hundred meters starboard of us. A few beams, black and sticking straight out of the sand. Probably shaken free during that last big quake or perhaps even exposed when the silt had been sucked off of it by the passing tsunami. I didn’t have much time to explore. Thought I’d leave it to an expert.” She pinched him in the ribs, then leaned back into his chest.

As a group, they watched the sun vanish with a last coy wink into the sea. It was their ritual. Barring a storm, they never missed a sunset while at sea. The ship rocked gently. In the far distance, a passing tanker winked a few lights. But they were otherwise alone.

A sharp bark startled Susan, causing her to jump. She had not known she was still a bit tense. Apparently the strange, wary behavior of the reef life below had infected her.

“Oy! Oscar!” the professor called.

Only now did Susan notice the lack of their fourth crewmate on the yacht. The dog barked again. The pudgy Queensland heeler belonged to the professor. Getting on in age and a tad arthritic, the dog was usually found sprawled in any patch of sunlight it could find.

“I’ll see to him,” Applegate said. “I’ll leave you two lovebirds all cozied up. Besides, I could use a trip to the head. Make a bit more room for another Foster’s before I find my bed.”

The professor gained his feet with a groan and headed toward the bow, intending to circle to the far side — but he stopped, staring off toward the east, toward the darker skies.

Oscar barked again.

Applegate did not scold him this time. Instead, he called over to Susan and Gregg, his voice low and serious. “You should come see this.”

Susan scooted up and onto her feet. Gregg followed. They joined the professor.

“Bloody hell…” her husband mumbled.

“I think you may have found what drove those dolphins out of the seas,” Applegate said.

To the east, a wide swath of the ocean glowed with a ghostly luminescence, rising and falling with the waves. The silvery sheen rolled and eddied. The old dog stood at the starboard rail and barked, trailing into a low growl at the sight.

“What the hell is that?” Gregg asked.

Susan answered as she crossed closer. “I’ve heard of such manifestations. They’re called milky seas. Ships have reported glows like this in the Indian Ocean, going all the way back to Jules Verne. In 1995, a satellite even picked up one of the blooms, covering hundreds of square miles. This is a small one.”

“Small, my ass,” her husband grunted. “But what exactly is it? Some type of red tide?”

She shook her head. “Not exactly. Red tides are algal blooms. These glows are caused by bioluminescent bacteria, probably feeding off algae or some other substrate. There’s no danger. But I’d like to—”

A sudden knock sounded beneath the boat, as if something large had struck it from below. Oscar’s barking became more heated. The dog danced back and forth along the rails, trying to poke his head through the posts.

All three of them joined the dog and looked below.

The glowing edge of the milky sea lapped at the yacht’s keel. From the depths below, a large shape rolled into view, belly up, but still squirming, teeth gnashing. It was a massive tiger shark, over six meters. The glowing waters frothed over its form, bubbling and turning the milky water into red wine.

Susan realized it wasn’t water that was bubbling over the shark’s belly, but its own flesh, boiling off in wide patches. The horrible sight sank away. But across the milky seas, other shapes rolled to the surface, thrashing or already dead: porpoises, sea turtles, fish by the hundreds.

Applegate took a step away from the rail. “It seems these bacteria have found more than just algae to feed on.”

Gregg turned to stare at her. “Susan…”

She could not look away from the deadly vista. Despite the horror, she could not deny a twinge of scientific curiosity.

“Susan…”

She finally turned to him, slightly irritated.

“You were diving,” he explained, and pointed. “In that water. All day.”

“So? We were all in the water at least some time. Even Oscar did some dog-paddling.”

Her husband would not meet her gaze. He remained focused on where she was scratching her forearm. The wet suit sometimes chafed her limbs. But the worry in his tight face drew her attention to her forearm. Her skin was pebbled in a severe rash, made worse by her scratching.

As she stared, bruising red welts bloomed on her skin.

“Susan…”

She gaped in disbelief. “Dear God…”

But she also knew the horrible truth.

“It’s…it’s in me.”

He was being hunted.