Giordino broke Pitt's revery. "Didn't you mention that woman you met in Egypt was going to Mali?"
Pitt nodded. "She's connected with the UN team from the World Health Organization. They were flying to Mali to investigate a strange epidemic that had broken out among the desert villages."
"Too bad you can't rendezvous with her," said Giordino, smiling. "You could sit under a desert moon with your arm around her, whisper of your exploits in her ear, and sift sand."
"If that's your idea of a hot date, no wonder you bat zero."
"How else can you entertain a geologist?"
"Biochemist," Pitt corrected him.
Giordino's expression suddenly turned serious. "Did it ever occur to you that she and her scientist buddies might be looking for the same toxin we are?"
"The thought crossed my mind."
At that moment Rudi Gunn hustled up from his lab below, his face haggard but broken by a wide grin. "Got it," he announced triumphantly.
Giordino looked at him, not comprehending.
"Got what?"
Gunn didn't answer. He just smiled and smiled.
Pitt knew almost immediately. "You found it?"
"The glop that's exciting the red tides?" Giordino muttered.
Gunn nodded.
Pitt pumped his hand. "Congratulations, Rudi."
"I was almost ready to give up," said Gunn. "But my negligence opened the door. I've been putting hundreds of water samples through the gas chromatograph, and haven't been checking on the inner workings as often as I should. When I finally took a look at the results, I found a coating of cobalt inside the instrument's test column. I was shocked to see a metal was being extracted with synthetic organic pollutants and finding its way into the gas chromatograph. After frantic hours of experiments, modifications, and tests, I identified an exotic organometallic compound that's a combination of an altered synthetic amino acid and cobalt."
"Sounds Greek to me," shrugged Giordino. "What's an amino acid?"
"The stuff proteins are made of."
"How can it get in the river?" asked Pitt.
"Can't say," replied Gunn. "My guess is the synthetic amino acid came from a genetic engineering biotechnology laboratory whose wastes are being dumped along with chemical and nuclear wastes at the source area. For it to naturally mix into the vicious pollutant that's causing the red tides after reaching the sea seems remote. I believe it's forming at a common location."
"Could it be a dump site with nuclear waste too?"
Gunn nodded. "I'm finding fairly high readings of radiation in the water. It's only another portion of the overall pollution and has no relation to our contaminant's qualities, but there is a definite connection."
Pitt didn't reply but looked again into the radar screen at the image of the gunboat, still out of eyesight astern. If anything, it had dropped farther back. He turned and scanned the sky for the fighter jets. They were still lazily clawing at the sky, conserving their fuel while keeping a distant watch over the Calliope. The river had widened to several kilometers and he lost sight of the armored cars.
"Our job is only half done," he said. "The next exercise is to target where the toxin enters the Niger. The Malians don't seem in any hurry to harass us. So we'll continue our survey upstream and attempt to wrap this thing up before they slam the door."
"With our data transmission system kaput, how do we get the results to Chapman and Sandecker?" asked Giordino.
"I'll figure something."
Gunn placed his trust in Pitt without hesitation. He nodded without speaking and returned to his cabin lab.
Pitt thankfully turned over the helm to Giordino while he stretched out on a deck mat under the cockpit canopy and caught up on his lost sleep.
When he woke up, the sun's orange ball was a third down over the horizon, and yet the air felt 10 degrees warmer. A quick check of the radar showed the gunboat was still dogging their stern, but the watchdog fighter jets were on a course back to their base to refuel. They were getting cocky, Pitt surmised. The Malians must have thought their quarry was in the bag. Why else would the fighters depart without being relieved by another flight? As he rose to his feet and stretched his arms and shoulders, Giordino handed him a mug of coffee.
"Here, this should wake you up. Good Egyptian coffee with mud on the bottom of the cup."
"How long was I in dreamland?"
"You were dead to the world for a little over two hours."
"Have we passed Gao?"
"Cruised past the city about 50 kilometers back. You missed seeing a floating villa with a bevy of bikini-clad beauties throwing kisses to me from the railings."
"You're putting me on."
Giordino held up three fingers. "Scout's honor. It was the fanciest houseboat I've ever laid eyes on."
"Is Rudi still reading strong toxin levels?"
Giordino nodded. "He says the concentration gets hotter with each passing kilometer."
We must be close."
"He thinks we're almost on top of the stuff."
Just for an instant something flickered deep in Pitt's eyes, a sudden gleam, almost as if something was created, something imagined that reflected from inside his brain. Giordino always knew when Pitt departed reality and traveled to some unknown destination. With a blink of his opaline eyes all recognition was gone, replaced with a view of another scene.
Giordino stared at him curiously. "I don't like that look."
Pitt came back down to earth. "Just thinking of a way to keep the Calliope from a despotic backwater jerk who wants it for his drunken orgies."
"And how do you expect to erase the possessive gleam in Kazim's eye?"
Pitt smiled like a reincarnated Fagin. "By conjuring up a dirty scheme to defeat his expectations."
Shortly before sunset, Gunn called from below. "We've crossed into clean water. The contamination just disappeared off my instruments."
Pitt and Giordino immediately turned their heads and scouted both shores. The river at this point ran on a slight angle from west of north to east of south. There were no villages or bordering roads to be seen. Only desolation met the eyes, level and barren without disruption all the way to the four horizons.
"Empty," muttered Giordino. "Empty as a shaven armpit."
Gunn emerged, staring back over the stern. "See anything?"
"Look for yourself." Giordino swung an arm like a compass. "The cupboard's bare. Nothing but sand."
"We have a break in the geology to the east," said Pitt, motioning at a wide ravine dividing the shore. "Looks as though it once carried water."
"Not in our lifetime," said Gunn. "Appears to have been a tributary into the main channel during wetter centuries."
Giordino studied the ancient streambed solemnly. "Rudi must have tuned in a video game. There's no contamination entering the river here."
"Swing around and make another run so I can recheck my data," said Gunn.
Pitt complied and ran several lanes back and forth as if mowing a lawn, beginning close to the shore and working out into the channel toward the opposite bank until his props churned silt on the rising bottom. The radar showed the tailing gunboat had stopped, the captain and his officers probably wondering what the crew of the Calliope was up to.
Gunn popped his head through the hatch after the final run. "Swear to God, the highest concentration of toxin comes from the mouth of that big wash on the east bank."
They all stared dubiously at the centuries-old dry riverbed. The rock-strewn bottom curled northward toward a range of low dunes in the desert wasteland. No one spoke as Pitt set the throttles on idle and let the yacht drift with the current.
"No evidence of toxic residue beyond this point?" questioned Pitt.
"None," Gunn answered flatly. "The concentration goes off scale just below the old wash and then disappears upstream."