“Any speculation as to the source?” Pitt asked.

Biazon shook his head. “We initially suspected industrial pollutants, which, regrettably, are an all too common source of environmental damage in my country. But my field team and I have scoured the impacted coastal region and failed to locate any heavy industrial businesses operating in the area. We also examined the coastline for obvious spillways or illegal dump sites but came up empty. It is my belief that the source of the kill originates at sea.”

“Perhaps a red tide?” Giordino said.

“We do experience toxic phytoplankton outbreaks in the Philippines,” Biazon said, “though they are typically seen during the warmer late summer months.”

“It might also be some covert offshore industrial dumping,” Pitt replied. “Where exactly is the impacted area, Dr. Biazon?”

Biazon glanced at the map, which showed Mindanao and the southern Philippine island groupings. “Off the province of Bohol,” he said, pointing to a large round island north of Mindanao. “Panglao is a small resort island located here, adjacent to the southwest coast. Its about fifty kilometers from our present position.”

“I can have us there in under two hours,” Stenseth said, eyeing the distance.

Pitt nodded toward the map. “We've got a ship full of scientists who can help find the answers. Bill, lay a course in to Panglao Island and we'll take a look.”

“Thank you,” a visibly relieved Biazon said.

“Doctor, perhaps you'd like a tour of the ship while we get under way?” Pitt offered.

“I'd like that very much.”

“Al, you care to join us?”

Giordino looked at his watch pensively. “No, thanks. Two hours will be just enough time for me to finish my project,” he replied, easing himself back down on the bench seat and drifting rapidly back to sleep.

The Mariana Explorer cruised easily through a flat sea and arrived at Panglao Island in just over ninety minutes. Pitt studied an electronic navigational map of the area that was displayed on a color monitor as Biazon denoted a rectangular area where the fish kill was occurring.

“Bill, the current runs east to west through here, which would suggest that the hot zone is located at the eastern end of Dr. Biazon's box. Why don't we start to the west and work our way east into the current, taking water samples at quarter-mile increments.”

Stenseth nodded. “I'll run a zigzag course, to see if we can gauge how far from shore the toxin is concentrated.”

“And let's deploy the side-scan sonar. Might as well see if there's any obvious man-made objects involved.”

Dr. Biazon watched with interest as a towed sonar fish was deployed off the stern, then the Mariana Explorer began following a dot-to-dot path laid out on the navigation screen. At periodic intervals, a team of marine biologists collected seawater samples from varying depths. As the ship moved to the next position, the collected samples were sent down to the shipboard laboratory for immediate analysis.

On the bridge, Giordino tracked the signals from the side-scan sonar. The electronic image of the shallow seafloor revealed an interweaving mix of flat sand bottom and craggy coral mounts as the ship sailed over the fringes of a coral reef. In a short time, his trained eyes had already discerned a ship's anchor and an outboard motor | lying beneath the well-traveled waters. As the monitor revealed each object, Giordino reached over and punched a mark button on the con| sole, which flagged the location for later assessment.

Pitt and Biazon stood nearby, admiring the tropical beaches of Panglao Island less than a half mile away. Pitt glanced down at the water alongside the ship, where he spotted a sea turtle and scores of dead fish floating belly-up.

“We've entered the toxic zone,” Pitt said. “We should know the results shortly.”

As the research vessel plowed west, the concentration of dead fish in the water increased, then gradually fell away until the blue sea around them grew empty again.

“We're a half mile beyond Dr. Biazon's grid,” Stenseth reported. “Judging by the water, it looks like we're well clear of the toxic zone.” “Agreed,” Pitt replied. “Let's stand by here until we see what kind of results the lab has found.”

As the ship ground to a halt and the sonar tow fish was retrieved, Pitt led Biazon down a level into a teak-paneled conference room, followed by Giordino and Stenseth. Biazon studied the portraits of several famous underwater explorers which lined one wall, recognizing the images of William Beebe, Sylvia Earle, and Don Walsh. As they were seated, a pair of marine biologists clad in the requisite white lab coats entered the conference room. A short, attractive female, her brunet hair tied back in a ponytail, walked to a suspended viewing screen at the front of the room, while her male assistant began typing commands into the computer-driven projection system.

“We have completed an assessment of forty-four discrete water samples collected, which were analyzed using molecular separation of existing toxic molecules,” she said in a clear voice. As she spoke, an image appeared on the screen behind her, similar to the navigation screen Biazon had noticed the ship tracking to earlier. A zigzag line line punctuated by forty-four large dots ran parallel to an outline of the pang lao Island shoreline. Each dot was color-coded, though Biazon noted that most of them glowed green.

“The samples were measured for toxic content in parts per billion, with positive results occurring in fifteen of the samples,” the biologist stated, pointing to a row of yellow dots. “As you can see from the chart, the concentration increases as the samples moved east, with the highest reading registered here,” she said, tracing past a few orange-colored dots to a lone red dot near the top of the map.

“So the source is from an isolated location,” Pitt said.

“The samples tested negative beyond the red point, indicating that it is likely of a concentrated origin spreading east with the current.”

“That would seem to dispel the red tide theory. Al, do the results mesh with anything we picked up on the sonar?”

Giordino walked over to the console and leaned over the operator's shoulder, typing in a quick series of commands. A dozen As suddenly appeared on the projection screen, overlaid at random points along the zigzag tracking line. Each AT was lettered, beginning with A at the bottom, proceeding to L near the top.

“Al's ”Dirty Dozen' hit list,“ he smiled, retaking his seat. ”We ran over twelve objects that appeared man-made. Mostly chunks of pipe, rusty anchors, and the like. Three items appeared that could be suspected culprits,“ he said, eyeing a sheet of handwritten notes. ”Mark Cwas a trio of fifty-five-gallon drums lying in the sand."

Every eye in the room jumped to the A'marked Con the overhead. The water samples on either side of the mark were all illuminated with green dots, which signified a negative test result.

“No toxins registered in the vicinity,” Pitt said. “Next.”

“Mark F looks to be a wooden sailboat, perhaps a local fishing boat. She's sitting upright on the bottom with her mast still standing.”

This AT was located adjacent to the first yellow dot. Pitt commented that it was still down current of the toxic readings.

“Strike two. But you're getting warmer.”

“My last mark is a little odd, as the image was just at the range of ij the sonar,” Giordino said, pausing with uncertainty.

“Well, what did it look like?” Stenseth asked.

“A ship's propeller. Looked like it was protruding from the reef. I couldn't make out any sign of the ship that went with it, though. Might just be a lone propeller that got bashed off against the reef. I tagged it at mark K”

Every voice in the room fell silent as their eyes found the A'marked Kon the overhead screen. It was positioned right above the red dot..;