Lauren immediately saw the parallel to Mercer’s idea. “Like a diving bell?”
“More like a bathysphere with an umbilical. Only we’re trapped under poison gas rather than water.” Because CO2 was one and a half times as heavy as air and they were only going to be twenty feet down, Mercer wasn’t concerned about keeping the tent pressurized. The frame would support the plastic sheets.
“How much time do we have?”
“I can’t tell without knowing how much gas is gushing from the lake. But we’re only a couple feet above where Ruben had his fire. We don’t have long. Can you climb a tree with the hose?”
“Damned right I can.” She went off, leaving Miguel to help Mercer level an area to set the lightweight tent.
The physics behind Mercer’s plan was simple enough but he wouldn’t know how well they’d carried out the execution until they were sealed inside the tent. A thousand things could go wrong, the worst being a miscalculation about the height of the hills and the top of the tree Lauren was climbing like an electrical lineman. If the mouth of the hose wasn’t high enough, CO2 would drain down into the tent, replacing the air, and smothering the three of them. He had enough tape to keep the tent airtight but there was nothing they could do if the hose was too low.
Mercer found a dozen candles in Gary’s duffel and set a few of them in a row running down to the shore of the lake, lighting them with one of the lighters Gary had also cached. The candle he placed closest to the lake wouldn’t even light. The next one placed at a slightly higher elevation burned for just a few seconds before it starved for air. The gas was creeping ever closer. Captain Vanik was still at the top of the tree, tying off the thick length of rubber hose.
“Come on, Lauren.” Another candle was snuffed. The CO2 was just a few feet below the tent.
“Almost got it.” A third candle went dark.
The top of the volcano was filling faster than he thought possible. He could see Miguel start to pant as his lungs sought oxygen. “Now, Lauren.”
As agile as a cat, she scrambled down the nearly branch-less tree. Miguel’s eyes were droopy as Mercer slid him into the tent, his young body succumbing to the narcotic effect of the gas much quicker than those of the adults. Before following Lauren into their cocoon, Mercer threw in a few items from Gary’s duffel and sealed them all inside by taping the plastic-covered flaps of the tent fly. The long day of exploration and the quick exposure to CO2 had already put Miguel into a deep sleep.
Mercer grabbed the end of the hose dangling through the tight slit he’d cut at the top of the tent. He crimped the rubber around the hand pump’s suction inlet. The pump itself resembled a cheap accordion with a one-way valve at its outlet. Mercer gave it a few squeezes, allowing the air it sucked from the top of the tree to blow across his face. So far, so good. While the tent was designed to hold three people, he still had to crawl over Lauren and Miguel to apply more layers of tape to where the hose entered the roof. He also needed to patch a few small holes. The remaining candles outside blinked out one by one, coils of smoke from their wicks barely discernible through the multiple layers of plastic. With surprising speed, the tent began to sag around its frame as the heavier CO2 pressed against the lower internal air pressure.
Knowing he’d need to maintain a rhythm for untold hours, Mercer began to work the pump. Once he’d matched pressures, he cut a tiny hole in the tent’s floor to prevent the air becoming fouled by their own breath. As the caldera filled to its maximum level, he’d need to adjust the hole in the floor to maintain equilibrium. After fifteen tense minutes he was satisfied that everything appeared set. By fighting the natural instinct to run, he’d just saved their lives. Not that they were safe by any stretch, but for a few moments he would savor the victory. He looked at Lauren and couldn’t help but grin.
She smiled back. “I saw all this stuff sitting in the boat when we came to the island and I still never would have thought of this in a million years.” She regarded him for a second. “When those explosives went off you’d already figured out a solution. I mean instantly. How?”
Asking Mercer that was the same as asking him to explain his entire thought process, something he himself couldn’t properly define. “I suppose it’s a memory trick.”
Lauren’s eyes widened. “You’ve done this before?”
Mercer laughed. “No, but I’ve read or seen something that triggered this idea. Maybe it was a story about a bathysphere, a biography of William Beebe or something. I honestly don’t know.” But he actually did know. Mercer could even recall the cover of the old National Geographic magazine he’d read as a boy that detailed the inventor of the bathysphere. He’d always considered his near-photographic memory to be his greatest single asset. “When the depth charges blew,” he continued, “I knew how the CO2 would build up and knew we needed an airtight bubble and a way to supply oxygen. The rest was just putting it all together.”
“Whatever trick you used, I’m grateful. I would have tried to row away.” She chuckled. “Fight my way out rather than think. And I thought I was smarter than that.”
The pump forced enough air into the tent so that Mercer and Lauren didn’t need to keep quiet to conserve oxygen as time trickled by. They also kept a candle lit as an early warning in case an unseen rip allowed CO2 into the tent. The single steady glow helped to dispel the horror of their predicament and the darkness that enveloped the mountaintop as the sun completed its arc.
At first their conversation was strained by the thought that a few millimeters of plastic were all that protected them from a swift death. As the first hours went by, they became more comfortable with their situation, and each other. Yet their conversation rarely strayed far from what had happened to Gary Barber and Ruben. The theories they batted around gave them more insight into each other than who was behind the helicopter attack. Mercer especially was impressed with what he learned. Lauren Vanik was filled with a sense of duty he thought people no longer had.
Two hours before midnight, the sound of bubbling gas finally stopped. For hours CO2 had vented explosively from the lake and the noise had become such a constant backdrop that it took several seconds for them to realize it had ceased. In the quiet that followed, Mercer suggested that Lauren finally get some sleep. She agreed only after he promised he would wake her in a few hours so she could spell him at the pump.
Before curling up, her voice took on an uncomfortable edge. “Ah, Mercer, we have a slight problem.”
“H’m?”
“We can go without food or water until morning, but I’ve got to, you know, pee, and I don’t think I’ll be able to hold it.”
“Me too,” Miguel called. He must have been awake for a while, waiting for the adults to bring up a problem he’d been struggling with for some time.
From the supplies Mercer had tossed into the tent, he dug around until he found a large steel saucepan and a lid. Lauren eyed him warily. “Don’t tell me a fine Southern woman such as yourself has never used a chamber pot?”
“I admit Thomasville, Georgia, isn’t the biggest place in the world, but we’ve had indoor plumbing for years and years.” She was still reluctant to take the pan from him.