“Okay, I'll need your help in pushing it back upright,” he said. “Let's try it on the count of three.”

Slipping his foot to the backside of the ring, he counted to three, then pulled his leg toward him. Summer pushed with her manacled hand and they gradually shoved the ring back to its original vertical position.

“Well, that was fun,” Dirk said while resting his leg. “Let's try it again.”

For twenty minutes, they toggled the ring back and forth, the movement gradually becoming easier as the tensile strength of the old iron weakened. With a last strong kick by Dirk, the ring finally snapped off its concrete base, freeing Summer's left arm. She immediately twisted her hand around and dug into the small side pocket of her silk jacket and produced the porcelain-handled nail file.

“I've got the file. Should I try on the handcuff itself or the mooring ring?” she asked.

“Go for the ring. Even though it's thicker, it will be much softer to cut through than the hardened stainless steel handcuffs.”

Using the small file like a hacksaw, Summer began grinding away at the base of the mooring ring. Working the file with any degree of accuracy beneath the murky river water and fading cavern light would have been a Herculean task for most, but Summer's extensive diving experience gave her a leg up. Years of exploring and excavating historic shipwrecks in foul visibility had heightened her sense of touch to the extent that she could nearly tell more about a wreck from her hands than by her eyes.

With some measure of hope, she felt the file cut rapidly through the outer layer of the rusty ring. Her confidence waned when the blade met up with the hardened inner core of the iron ring and progress slowed to a snail's pace. The rising water was now level with her chest and the pending urgency unleashed a surge of adrenaline. Summer worked the blade back and forth as fast as she could muster underwater, gaining ground millimeter by millimeter. Taking quick breaks from sawing, she placed her hands on the iron ring and pushed and pulled it to weaken the metal. Alternating sawing and prodding with an intermittent gulp or two of river water, she at last broke through the ring and freed herself.

“Got it,” she exclaimed with victory.

“Mind if I borrow that file?” Dirk asked calmly, but Summer had already kicked and swum her way over and begun cutting into the ring grasping his right hand. As she worked the file, she mentally noted that it had taken her roughly thirty minutes to cut through the first ring and that the water level was now nearly to their shoulders. The water was rising faster than she anticipated and would be well above Dirk's head in less than an hour. Despite aching fingers and limbs, she rubbed the file ferociously against the iron.

Dirk, waiting patiently as Summer filed away, began whistling the old 1880s tune “While Strolling Through the Park One Day.”

“That's not helping,” Summer gasped, then smiled to herself at the silly tune. “Now I won't be able to get that ridiculous song out of my head.”

Sure enough, he quit whistling, but the tune kept replaying over and over in her head. She was surprised to find it became a good sawing mantra that provided a rhythm to her hand movements.

While strolling through the park one day,... With each syllable, she applied a cutting stroke to the iron, creating an efficient sawing cadence. in the merry merry month of May.

I was taken by surprise by a pair of roguish eyes.

In a moment my poor heart was stole away.

The water level had now crept up over her chin and she found herself taking in gasps of air, then submerging briefly to keep the file clawing in one spot. Dirk was beginning to strain to keep his face out of the water while applying alternating tugs and shoves on the ring as Summer sawed tirelessly on. A muffled metallic ting finally echoed beneath them as the ring broke loose under their combined pressure.

“Three down, one to go,” Summer gasped, taking in a lungful of air after being submerged for several seconds.

“Let me give you a breather,” Dirk said, grabbing the file from Summer with his free hand. The release of his right hand gave him a few extra inches of breathing room, but it was not enough to file the last mooring ring without submerging. Taking a deep breath, he ducked under the surface and began filing rapidly on the ring that held down his left wrist. After thirty seconds, he bobbed to the surface, sucked in some fresh air, and plunged back under. Summer stretched her cramped fingers, then swam to Dirk's left side and waited for him to surface. Like a pair of tag team wrestlers trying to floor Hulk Hogan, they passed the file back and forth and ducked underwater, attacking the iron ring with muscle and fervor.

As the minutes wore on, the water level in the cavern crept higher and higher. Each time Dirk surfaced for a gasp of air, he felt himself stretching farther and farther to raise his mouth and nose above water. The handcuff shackle on his left wrist dug into his flesh as he instinctively yanked hard to escape the clutch of the massive barge weight.

“Save your strength for getting out of here,” he told his sister as the inevitable truth drew closer that they were running out of time. Summer said nothing as she grabbed the file out of his hand and plunged back beneath the surface. Dirk half-floated with his head tilted back, his face just barely out of the water, drawing a few deep breaths. He could feel the water wash over his face in ripples and stretched for one last deep breath before pulling himself under. Grasping Summer's wrist, he pulled the file out of her hand and began a last furious rush at cutting through the iron. Feeling the gouge with his thumb, he could tell that they had cut only a third of the way through. There was just too far to go.

The seconds felt like hours as Dirk made a final effort to break free. He could feel his heart beating like a bass drum as it struggled to pump oxygen into his depleted blood. In the murkiness, he could feel that Summer was no longer by his side. Perhaps she had finally taken his advice and sought escape. Or perhaps she just couldn't bear to be with him during his final gasp of life.

He paused from filing for a second to try pushing his weight against the ring. He could generate little leverage, however, and the iron ring held firm. Again, to the file he went, making furious strokes with the flimsy metal blade. His ears began pounding with each beat of his heart. How long had he been holding his breath now? A minute, two minutes? It was difficult to remember.

Light-headedness fell over him as spots began to creep into his vision. He exhaled what remaining air was left in his lungs and fought the temptation to open his mouth and gulp in. His heart pounded stronger and it became a mental fight against succumbing to panic. A light current seemed to push him away from the mooring ring, but his hand muscle grasped the file tightly in a death grip. A white veil was being drawn across his vision and a distant voice inside was telling him to let go. As he fought a last battle with the voice, his ringing ears detected a deep thump and then a strange vibration rippled up his arm and through his body just before his mind tumbled into a dark and empty void.

Summer knew that they were at least twenty minutes from filing through the iron ring and that there would have to be another way to free her brother. Abandoning Dirk, she dove to the cavern floor, searching and groping for another tool or device, anything that would help break the manacle. But the flat, sandy bottom yielded nothing, just the row of mooring weights, one after the other. Kicking ahead with one hand guiding along the blocks of concrete, she touched a large chunk of concrete that had broken off one of the weights when it had been dropped too close to another. Gliding beyond the debris, she reached the last block, where she felt something flat and squishy like soggy leather fall away in her hand. A harder piece beneath it was narrow and curved, which she identified as the sole of a boot. A stick leaned against it, which she started to grab, then let go in horror. It was no stick, she could tell, but the femur bone of a skeleton that was still wearing the boot. Another victim of Kang's savagery, the corpse had long ago been left chained to the anchor. Recoiling, she turned to swim back toward Dirk and bumped her head square into the fallen chunk of concrete. The broken piece was roughly square shaped, weighing about ninety pounds. She surveyed the block with her hands to get around it, then hesitated. It might be the answer, she decided, and was the best she could do under the circumstances.