Cabrillo had no desire to get caught in a cross fire from nervous border guards, so rather than cross this particular line he was going to go under it.

The RHIB was loaded to the gunwales with iron plates tons of them enough to quadruple the shipping costs of sending the boat unladen. Mark Murphy and Eric Stone had figured out the exact amount needed to pull off Juan's stunt, and now they were about to find out if his two resident geniuses were right.

Wordlessly, they got to work. Jerry and Mike installed the engine covers and made sure they were watertight while Mark double-checked that all their dive bags full of equipment and weapons were securely tied down. After inspecting the open cabin for anything that might get damaged by emersion, Juan handed over the four Draeger rebreathers. Unlike Scuba tanks, there was no telltale trail of bubbles from the German-made device. They worked by scrubbing carbon dioxide from the closed-loop system and adding oxygen from a small tank when gas ratios tipped dangerously.

The men wore micro-thin black diving suits, not so much for thermal protection the water was blood warm but to cover their white skin. Their dive shoes had thick rubber soles and detachable flippers in case they needed to leave the water in a hurry.

Would be nice if we could do this closer to the border, Jerry Pulaski commented. It was an observation hiding a mild complaint.

Sure would be, Juan agreed, suppressing a grin. Satellite pictures showed the next town on the river was five miles downstream. Again, if he was part of the Argentine junta, he would pay some local wharf rat to drop a dime if he saw or heard anything suspicious. In this part of the world, patriotism was a poor substitute for a full belly, so the team was in for a long night. Cabrillo turned to Murphy. You want the honors?

Hell no, Mark said. If we got it wrong, you're going to make Eric and me pay for the boat.

Juan shrugged. Good point.

Standing chest-deep in the current, he reached over one of the inflatable fenders and opened a release valve. Air hissed from the valve under high pressure until the black rubber was limp. He nodded to Jerry to do the same on the other side, and soon they had half of them emptied. Water sloshed over the gunwale as the boat sank deeper into the river. Cabrillo and Pulaski pushed down on the hull. The boat sank farther and remained submerged, though the bow soon rose to the surface. More air was released until the RHIB was neutrally buoyant and perfectly balanced.

Not surprisingly, the calculations for the added ballast had been spot-on.

The team struggled into their rebreathers, fit full masks over their faces, and performed a communications check. There was little chance of running into crocodiles or caimans, but all had spearguns fitted into holsters strapped to their thighs.

Juan sliced the rope securing the RHIB to the hut and let the current take them. With each man holding a line attached to the boat, they swam their ungainly charge into the middle of the river. To Cabrillo, it felt like they were trying to herd a hippopotamus.

They stayed close to the surface for the first few miles, swimming lazily with the river's not-insignificant current. This far from the light pollution of any cities, the sky was a vaulted dome of glittering stars, so bright and so numerous it seemed as though night in this part of the world was silver and not black. It was more than bright enough to see both banks of the river and to keep the wallowing boat in the center of the channel.

Only when they neared the next village did the men dump air from their buoyancy compensators and take the RHIB down close to the bottom. Juan had taken a compass bearing before slipping below the surface, and he steered them by watching the dial's luminous face. It was an eerie feeling, swimming in water as dark as ink. With the temperature close to his own body's, it was as though he'd been denied all tactile sensation. They drifted for a mile, the men lazily finning to maintain steerage, before Cabrillo ordered them back to the surface.

The isolated village was well behind them, and they found they had the river to themselves. Even had there been traffic, their black gear, and the fact that only parts of their heads were exposed, would lead any native to believe the team was just a couple of branches being slowly swept down toward Argentina.

Hours rolled away. It was a faint glow emanating around the next bend that told them they were approaching the border. During their briefing, they had all seen satellite shots of the area. On the Paraguay side was a three-hundred-foot concrete quay fronting tumbledown warehouses and a customs shed. The sleepy little town was maybe four streets deep and equally wide. A white-steepled church was the tallest building. In response to the troop buildup, the local military commander had brought a detachment of soldiers to town. They were camped just north of the village in a field that ran right to the river's red-clay bank.

The Argentine side was almost identical, except there were at least five hundred soldiers garrisoned there, and they had strengthened their position by deploying search lights on spidery towers to sweep the black river, and strung thickets of concertina wire on the dirt road connecting the two towns. The satellite pictures showed two slim boats tied to the pier near where it looked like the military was headquartered. To Juan's eye they appeared to be Boston Whalers, and, if he had to guess, they were probably armed with machine guns and possibly grenade launchers. They would be a problem if things got hairy.

Keeping close to the bottom, but not touching it so the hull didn't disturb the silt and leaves and kick up a telltale wake, the men swam through the formidable gauntlet. They knew they had reached the Argentine position when a shaft of light pierced the dark water. They were too deep and the river too muddy for anyone on shore to see them, but they steered away from the silvery glow anyway. On the surface, the two men in the tower watched whatever the beam revealed empty water slowly flowing southward.

Cabrillo and the team remained submerged for another hour, only coming up when the border was miles behind them. It took another hour of drifting silently to reach a nameless tributary seen earlier from the satellite pictures. This time, the men had to work against the current, wrestling the unwieldy craft against the flow. Twenty minutes of struggle gained them only a hundred yards, but Juan called a halt, judging they were far enough upstream to keep them from potentially prying eyes.

He sighed as he stripped off the heavy Draeger set and laid it into the half-sunk boat. That feels good.

My fingertips look like white prunes, Mark complained, holding them up to the moonlight.

Quiet, Juan admonished in a whisper. Okay, boys, you know what's next. The quicker we get it done, the more shut-eye we get.

The steel plates used to lower the RHIB's profile weighed fifty pounds each, a not-unreasonable load for men in peak physical condition, but there were hundreds of them that had to be lifted over the gunwale and dumped into the river. The men worked like machines, Jerry Pulaski especially. For every plate Murph or Mike Trono got over the side, he moved two. Slowly, so slowly, the boat began to emerge like some slimy amphibian from the primordial ooze. Once the sides cleared the surface, Murph engaged a battery-powered pump. The steady stream of water sounded like a babbling brook.

It took an hour, and when they were finished all four rolled onto the still-wet deck and lay like dead men.

Juan was the first to rouse himself. He told his men to sleep, and let Jerry know he would have second watch. The night sounds of the jungle were punctuated by the occasional snore.

Two hours later, shortly after dawn, the RHIB left the small tributary and returned to the river proper. The air cells they had emptied remained limp, but on such smooth water, and with such a light load, it wouldn't affect the boat's capabilities.