A nearby blowhole in the rock spewed a fountain of sludgy seawater with a ringing bellow, as if the ocean itself were gasping its last breath.

Ducking under the spray, the pair of men worked north along the beach, traversing a narrow trail of clear sand between the foulness of the tidal zone and steep jungle-shrouded cliffs.

“Remind me to skip the seafood buffet back on the ship,” Monk mumbled through the rasp of his respirator. He was glad for his suit’s canned air. He could only imagine the reek that must accompany this tidal graveyard.

He was also relieved his partner, Dr. Lisa Cummings, had remained back aboard the cruise ship on the other side of the island. The Mistress of the Seas floated in Flying Fish Cove, safely upwind of the sickening pall that wafted across the island from the toxic soup on its western side.

But others had not been as lucky.

Upon arriving at daybreak, Monk had witnessed the hundreds of men, women, and children being evacuated from the island, all in various states of contamination: some blind, others merely blistered, the worst with skin dying off in pustulant slides. And though the toxic readings were rapidly declining, the entire island was being cleared as a safety precaution.

The Mistress of the Seas, a giant luxury cruise ship out on its maiden voyage among the Indonesian islands, had been evacuated and diverted, turned into an emergency medical ship. It also served as the operations center for the World Health Organization’s team, called in to discover the cause and source for the sudden poisoning of the surrounding seas.

It was also why Monk was out here this morning, seeking some answers in the aftermath of the tragedy. Back aboard the ship, Lisa’s skill as a medical doctor was being put to hard use while Monk’s training had him tromping through this cesspool. Because of his expertise in forensics — medical and biological — he had been handpicked for this particular Sigma assignment. The op had been classified as low risk — survey only — an operation to ease him back after taking three months off for family leave.

He shied away from that last thought. He didn’t want to think of his little baby girl while slogging through the filth here. Still, it couldn’t be helped. He flashed back to Penelope’s blue eyes, pudding cheeks, and impossible corona of blond hair, so unlike her father’s shaved head and craggy features. How could something so beautiful share his genes? Then again, his wife may have stacked the deck in that department. Even here, he could not dismiss the ache in his chest, a physical longing for them, as if a tether bound him as surely as any umbilical cord, a sharing of blood between the three of them. It seemed impossible he could be this happy.

Up ahead, his guide, Dr. Richard Graff, a salt-hardened oceanic researcher out of the University of Queensland, had dropped to one knee. He knew nothing of Monk’s true identity, only that Monk had been recruited by the WHO for his expertise. Graff settled his plastic sample case atop a flat shelf of rock. Through the face shield, the man’s bearded countenance was tight with worry and concentration.

It was time to get to work.

The pair had been dropped off in an inflatable rubber Zodiac. The pilot, a sailor from the Royal Australian Navy, remained at the boat, beached beyond the kill zone. An Australian Coast Guard cutter had arrived to oversee the island’s evacuation.

The remote island, resting fifteen hundred miles northwest of Perth, was still Australian territory. First discovered on Christmas Day in 1643, the uninhabited island was eventually colonized by the British to take advantage of its phosphate deposits, setting up a major mine here, employing indentured workers from throughout the Indonesian islands. And though the mines were still in operation, the tropical island’s main industry had turned to tourism. Three-quarters of the island’s highlands, thick with rain forests, had been declared national parklands.

But no tourists would be flocking here anytime soon.

Monk joined Dr. Richard Graff.

The marine researcher noted his arrival and waved a gloved hand to encompass the massive die-off here. “It started a little over four weeks ago, according to reports of some local fishermen,” explained Graff. “Lobster traps were found full of empty crustacean shells, the flesh dissolved away inside. Trawling nets blistered hands when pulled from the sea. And it only grew worse.”

“What do you think happened here? A toxic spill of some sort?”

“No doubt it was a toxic assault, but it was no spill.”

The scientist unfolded a black collection bag, emblazoned with a hazardous chemical warning, then pointed to the nearby surf. The waters frothed with a foamy yellowish slurry, a poisonous stew thick with meat and bones.

He waved an arm. “That is all Mother Nature’s handiwork.”

“What do you mean?”

“You’re looking at slime mold, mate. Composed of cyanobacteria, an ancient predecessor of the modern bacterium and algae. Three billion years ago, such slime flourished throughout the world’s oceans. And now it’s on the rise again. It was why I was called in here. Such organisms are my primary area of expertise. I’ve been studying such blooms out near the Great Barrier Reef, specifically one called fireweed. A mix of algae and cyanobacteria that can cover a soccer field in less time than it would take you to eat lunch. The bloody creature releases ten different biotoxins, potent enough to blister skin. And when dried, it can aerosolize with the burning force of pepper spray.”

Monk pictured the devastation back at The Settlement, the island’s largest township. It lay not far from the bay here, in the path of the tradewinds. “Are you saying that’s what happened here?”

“Or something like it. Fireweed and other cyanobacteria are blooming all across our oceans. From fjords of Norway to the Great Barrier Reef. Fish, coral, and marine mammals are dying off, while these ancient slimes, along with venomous jellyfish, are blooming. It’s as if evolution were running in reverse, the oceans devolving into primordial seas. And we’ve only ourselves to blame. Runoff of fertilizers, industrial chemicals, and sewage have been poisoning deltas and estuaries. Overfishing of the past fifty years has driven the population of large fish down by ninety percent. And climate change is acidifying and warming the waters, lessening its ability to hold oxygen, suffocating marine life. We are rapidly killing the seas beyond the ability to heal.”

With a shake of his head, he stared out at the dead pool. “In its wake, we are seeing the return of seas from a hundred million years ago, teeming with bacteria, toxic algae, and venomous jellyfish. Such dead spots are found all around the world.”

“But what caused this one?”

That was the question that drew them all here.

Graff shook his head. “A new unidentified slime mold. Something we haven’t seen yet. And that’s what scares me. Marine biotoxins and neurotoxins are already the most potent poisons in the world. So nasty that they are beyond even man’s ability to duplicate. Did you know saxitoxin, from bacteria in certain shellfish, has been classified by the United Nations as a weapon of mass destruction?”

Monk grimaced through his face shield at the seas here. “Mother Nature can be a nasty bitch.”

“The greatest terrorist of them all, mate. Best not to piss her off.”

Monk didn’t argue.

With the biology lecture over, Monk bent down and helped organize the collection kits. He struggled, fighting the plastic gloves of his suit. He was further compromised by a numb left hand. Maimed after a previous mission, he now wore a five-fingered prosthesis, state-of-the-art, chocked full of the latest in DARPA gadgetry, but synthetics and bioelectronics were not flesh. He cursed a bit as he fumbled a syringe into the sand.