Tidal Rip

entrance into a building, where he changed to a dark green flight suit and helmet. He pulled down the helmet’s sun visor and used a different exit. He climbed into the helicopter. It took off and went south, following the hills along the coast to Paranagua.

The view was breathtaking, but Jeffrey couldn’t enjoy it. Instead his head was filled with nautical charts, with curves and lines and ranges and bearings. In his mind, over and over again, he pictured that Argentine flying boat landing at Mar del Plata.

Somewhere out there, way down south, out beyond Argentina’s continental shelf, Ernst Beck and von Scheer are waiting. To strictly comply with the Axis rules of engagement for handing German atomic warheads to the Argentines, so far as our naval intelligence understands them, he’ll need to stay at least two hundred miles from the coast…. Probably a bit farther, since exactly two hundred miles would be too obvious. That would put Beck out beyond the far edge of the continental slope, in water as deep as his — or Challenger ’s — crush depth.

Then there’s the whole other question, how fluid and changeable those Axis ROEs might be depending on what unfolds in the next few hours. It’s total war now. Nothing’s guaranteed.

At Paranagua, the helicopter landed at a small civilian airport. A troubled Jeffrey went into a hangar and got into another van. During the short ride, he changed into his wet suit — which someone in the Rio bunker had kindly hung up to dry while he had met with President da Gama.

The van let Jeffrey out at a auxiliary naval installation. There, he boarded a Brazilian Navy transport helo. In the helo were open-circuit conventional scuba compressed-air tanks, secured for the flight with bungee cords and nylon strapping.

Jeffrey found this security shell game of clothes and cars and helicopters dizzying. He hoped it would be at least as confusing to the enemy, if they even realized he was in Brazil.

As he buckled in tight, he could see out a window on the starboard side of the aircraft. The helo took off, and Jeffrey continued his fast journey south, to catch up with USS Challenger.

He’d chosen the starboard side so he faced inland. From the helo he kept staring, preoccupied, at the distant horizon to the west.

The Iguazu Falls are three hundred miles away, in that direction. Will I be able to see a flash from here, when the atomic warhead goes off?

In the silt-obscured deafening water above the falls, the current tugged at Felix frighteningly. Only the first length of climbing rope, anchored to a thick treetrunk onshore, kept him and his men from being swept away. If the rappelling buckles on their weight belts failed and they couldn’t grab the neutrally buoyant rope and cling by hand, they’d go over the edge and fall hundreds of feet into the torrent to be bashed to pulp on the rocks below. Each man had a collapsible, lightweight metal river-crossing stick to help him gain some purchase against the bottom — but the sticks had not been designed for any river crossing like this.

As team leader, Felix went first and took the greatest risks. He kept below the surface as much as he could, using his Draeger. To raise his head to see what the Germans were doing always drew fire — not from the hotel, but from kampfschwimmer who’d already made it partway out into the river and had cover on a small island.

A continual hiss and rumble assaulted his ears underwater. The river made noise as it scoured the bottom and pelted past obstructions. The hard impact of the falls at the base of the cliff sent heavy vibrations back up through the rock, and this noise too came through the water from the rock.

Felix knew he was coming to the end of his rope, literally. He had to find an anchor point. The water was so thick with silt, it was impossible to see. If he wasn’t careful, the magnitude of its flow could tear the dive mask off his face into oblivion.

All things considered, it wouldn’t make much difference. I might just as well work with my eyes closed anyway.

Felix dived a few feet deeper. He tried to find the bottom again as the submerged riverbank sloped down. The farther out he moved the more insistent the surging current force became. Any moment, an uprooted tree weighing tons could wash down the river and smash right into him. As he whipped around in the turbulent flow near the end of the anchoring rope, he might be impaled on a steel rebar projecting from a broken concrete abutment of the now-damaged upper tourist walkway. There were hidden reefs and rocks, which might knock him unconscious to drown. Felix decided he’d better let some gas out of his buoyancy compensator to make himself heavy and gain more traction.

Submerged in brownish darkness, he touched the pebbled bottom with his flippered feet, standing in a low crouch sideways to the current to minimize his water resistance. The pressure in his ears told him he wasn’t dangerously deep. The men tried to steady him by steadying their parts of the rope — they certainly couldn’t see him from even a few yards away, and could only guess at what he was trying to do from minute to minute. The anchor rope, the lifeline, was his sole connection to the team.

Felix kept his river-crossing stick upstream of him, slanted down into the flow as he leaned into it. The stick helped break the current, while the pressure of the current lodged the stick against the bottom and levered its high end down on his chest. This gave him firmer footing and added stability as he inched along. Felix began to search the bottom blindly, systematically, by touch alone. Sometimes he used the stick instead to cast about in order to give himself greater reach. He became afraid of losing all sense of direction, and wandering unknowingly right over the edge of the falls.

Finally he found what he was looking for before it found and pierced or fractured him. A subtle back swirl in the feel of the current just downstream was his guide. He’d located the remnants of one of the walkway support piers. To work, Felix now required both hands. He collapsed his crossing stick and wrapped its lanyard tighter around his wrist so he wouldn’t lose it. The intense flow of the river still dragged at him constantly, and its hiss and rumble were relentless in his ears. No sunlight penetrated from the tumultuous surface above.

Felix took a free end of the coil of rope draped over his torso and deftly secured it to the bent steel bars that jutted from the concrete of the pier. Using this new length of rope as his safety anchor now, he secured the end of the first rope to the pier, then tugged a signal, which told the team that the far end of their rope was secure, and he was ready to advance another hundred yards. Keeping himself on a short leash for the moment, he let more gas into his buoyancy compensator.

Felix popped his head above the surface; he had to squint in the sudden brightness. He could barely make out the cluster of boulders that was his next objective. The noise of the falls was much louder with his ears out of the water. He kicked with his swim fins to try to lift his head high — the waves that were created as the river converged on the falls, and split into channels between all the islands and rocks, made it hard to see far.

Small splashes raised up all around him. Felix ducked below and heard the impact of the bullets against the surface. Those German MP-5s weren’t accurate for long-range sniping, but one lucky hit from a spray of rounds would still have high velocity, enough to kill any man it struck. Felix knew his team had to reach that cluster of boulders soon, and leave a man behind there temporarily in order to give the rest of them covering fire.

Felix was growing tired. His team had reached a flat little island on the very edge of the falls. It was covered in thick green underbrush, and he used this for concealment as he crawled forward. His men followed.

For a moment Felix paused to rest and gave hand signals for his team to do the same. Here, the noise of the falls was overwhelming. Speech was out of the question.

Felix lay on his back, supporting his Draeger with his arms, and glanced up at the sky. Streaks and fluffs of white cloud drifted peacefully far above. Butterflies swarmed, in amazing numbers, immune to any sense of danger; some were vivid turquoise with wingspans of four inches. He sighed and rolled over onto his elbows and knees, fighting the weight of his Draeger, then crept to the side of the island for a broad field of view in order to judge the enemy’s progress. The Germans had a head start and a clearer plan, but he hoped their pace would be slowed by the weight of the bomb.

Felix felt his way gingerly through the underbrush. Suddenly he felt nothing in front of him at all. He crawled forward inch by inch, very carefully, and peeked between the leafy ferns and branches.

He was on the verge of a gaping precipice two miles across. Curving wide around both sides of him, literally hundreds of waterfalls poured down. Brown water churned into white as he watched. Droplets turned into foam that turned into spray. Thick sheets of water ran over the edge in unimaginable quantities, as if the supply would