Puffs of cottony clouds drifted across an azure blue sky. The scenic view hung above Sarah and the caldera lagoon on the lower flank of Cerro Yglesia. The dormant volcano rose up from the jungle floor, its summit looming high above their heads. Dr. Graham must have been right about it being inactive. She didn't smell the slightest hint of sulphur dioxide. If magma were present in a subterranean chamber, the gas could permeate through the soil and seep up to the lagoon. She wasn't an expert on volcanic activity by any stretch of the imagination, but even now, she didn't consider it wise to refill their canteens here.

Sarah had been standing with the rest of the group as they discussed the meaning of the third and final riddle. Now that they found the lagoon, the question was what to do next? Everyone had a different take on their next step. What to do? What to do? With tensions running high, she walked away to be alone with her thoughts.

She recalled the key words that Dr. Graham emphasized earlier: swallows and mist.

Sarah tuned everyone out, letting their voices drift away with the clouds. She started with the word, mist. It seemed obvious it should come first. She didn't know why, just her instincts.

At the moment, there was no mist of any kind issuing from the lagoon or the caldera beneath it. She pondered the possibilities. Maybe in the 1800's, a mist had wafted from the water's surface? The volcano could have been active two hundreds year ago, heating the lagoon and producing steam. That seemed the most likely scenario. Or maybe not? There was a distinct possibility that Captain Bennett Graham's riddle had been referring to clouds hovering low on the mountain, like fog. She supposed that might be possible at certain times of the year. But one thing was for sure, there was no mist on the caldera now. Then again, the whole mist thing could have been a ruse, the captain's imagination? A decoy? Who knew?

Maybe the word mouth was more important than mist? Undecided, she moved on to the other key word, swallows. Then she realized...a mouth is something that swallows.

Sarah stared at the water. It was difficult to describe its size or compare it to anything, but she estimated it at roughly two hundred feet in diameter. She could see the bottom. It had to be forty to fifty feet down.

Jake, Dylan, and Tony walked up, as did Savannah, followed by Rachel.

Dr. Graham stood a few feet away, hand on his chin. They had wrapped up their discussion and now it looked like they'd come to a decision, and the doctor was pondering it.

"We think there's a drain at the bottom of the lagoon," Dylan said. "Hence, the mouth that swallows."

Savannah crossed her arms and glared at Sarah. "We believe there's an earthen plug, and we think someone needs to go pull it."

"Fifty feet of water with no dive gear? Are you kidding me?"

"A free dive," Jake said. "And I'm gonna do it."

"Are you serious? You have no idea if, or even where, a drain might be."

"I'm an experienced diver, Sarah, I can do it. Don't sweat it." He gave her one of his convincing grins. "Besides, if I didn't agree to it Tony would have."

Savannah continued to stare at Sarah.

"What?"

"Nothing."

"I'm going," Jake said. "That settles it. There's nothing to worry about."

Sarah cocked her head. "What if you find the plug? How are you going to pull it out? And if you do..."

"It's not that big of a deal." Jake turned to the water. "It's clear and calm, and there's not any marine threats in there. I'll just have to hold my breath...for a little while."

"No. I won't let you do it."

"Won't let me? Really?"

"We both know...we all know who should be the one to do this." Sarah looked at Savannah who diverted her eyes with a quirky smile. Off to the side, Dr. Graham glanced at Sarah out of the corner of his eye, a grin spreading across his face.

"Sarah...no" Jake said.

"You're trying to play this off like all you have to do is hold your breath, but there's something far worse to worry about." Sarah stared at him resolutely. "Yes, I'll do it. And we all know why."

Dr. Graham waltzed over and said, "Because you're the only one with the strength to pull the plug. Wherever it is down there, and whatever it's made of, it will have the weight of the entire lagoon bearing down on it, especially when you pull it and the suction starts."

Sarah said, "Funny how neither of you want to do it." She jabbed her eyes at Dylan and Savannah. "Don't." She threw up a hand to stave off a rebuttal. "I'll do it."

For another solid minute, Jake tried to sway her, but she would have none of it. She was determined.

Sarah peeled off her clothes to reveal her swimsuit. She was glad she chose to wear it under her clothes. It had come in handy once again.

She turned to Jake. " I'll be okay, trust me."

"This is crazy."

"Maybe, but we've made it this far..."

"But why you?"

"I think the better question is...why not me? Everyone knows what the Ocean Blue serum did to me. I can't hide it anymore."

For a long moment, he kissed her on the forehead. Then he nodded for her to go. He had given up on trying to persuade her not to do it, and Jake Solomon didn't give up on anything easily.

Sarah didn't wait for another round of debate. Instead she dipped her bare foot into the water to test it, and then she splashed in. More determined now, she stroked into the middle of the lagoon, adjusting to the coldness wrapping around her body.

Floating, she swiveled and waved to Jake. Then she took a deep breath and dove down, kicking to the bottom.

Sarah felt most at ease underwater, but this was a unique situation. She had to use her mind as much as her newfound strength and stamina. Twenty feet from the bottom, she hovered in place, eyes scanning the clear depths. If she were a drain, where would she be? Better yet, if she were a volcano, where would she erupt?

As she observed the bottom, an answer came to mind, but before she could give it consideration, she realized something.

She had held her breath underwater for over a minute and felt no need to return to the surface. So she swam, finning along, inspecting the rocky bottom. After an undetermined amount of time, she scissor kicked upward and broke into the open air.

"Sarah," Jake called out. "You've been under for over three minutes. Are you alright?"

"I'm fine. No problems...as of yet," she replied and dove toward the bottom.

Again, she wondered where a possible drain hole might be...and where the volcano might erupt?

She kicked for the surface and emerged. "I'm okay," she said to Jake in particular. "I'm just strategizing."

She spun in the water, gauging her position above the caldera. If the pressure in the volcano built evenly, it'd blow in the exact center. Truth was, it might not have happened that way. The most recent eruption may have occurred hundreds, if not thousands of years ago. She didn't know; she wasn't familiar with the volcanic history of the island. But when it had blown, there was a chance the blast was concentrated in the middle.

Sarah adjusted her position until she believed she was directly above the center of the caldera. Then she dipped under and descended.

At the bottom, she examined the floor of the lagoon. Again, her ability to hold her breath came into play. Curiously, she ran her fingers across the bottom, nudging aside small rocks and silty debris. She was feeling for irregularities and uniformities. Her hand felt bumps and smooth patches, and then a much bigger flat area.

She brushed aside the debris with her hand, scooting it out of the way until she'd cleared off an area of silt and rocks at least four foot square. It was only then that her body told her she needed to breathe.

Sarah made it to the surface and gasped for air, satisfying her lungs.

"Are you okay?" Jake said from the bank.

"How long was I under?"

"You don't want to know."

"I think I found something," she hollered.

"What is it?" Savannah replied.

"Wouldn't you like to know." And Sarah dove under.

Back at the spot she'd cleared off, she went to work again.

With her fingers, she inspected a rounded outline on the bottom. To increase her sensitivity, she closed her eyes and tuned in to the task at hand. She was onto something; it was only a matter of time and chance, the process of elimination.

Along the outline, her fingers stumbled on a deeper groove in the bottom. She started working it, scooting fine sand out of the way. As she moved the debris aside, she became more optimistic and enthused with her progress. She had discovered something.

But it wasn't an earthen plug like Savannah suggested. It was a round stone as big as a sewer manhole cover.

After surfacing once more, and describing her find, she descended and made her first attempt to move the stopper from this giant bathtub. With renewed energy, she inserted the fingers of both hands into the circular groove running around the plug. She searched for a firm grasp but realized she needed to drive her fingertips deeper into the gap between the stone and the blast rim of the caldera.

With her fingers buried in the tiny space all the way to her palms, she tried to lift it free, but she needed to dig even deeper. She needed to somehow work her fingers under the stone.

Just when she thought she might have to emerge for another breath, the edge of the outer blast rim crumbled beneath her fingertips. Sarah dug in and heaved the stone up, straining with every ounce of strength in her body. As she raised the plug, immediately, a vacuum-like force sucked the water and the silt around her feet, and pulled it into the hole.

Fighting against the suction, Sarah hoisted the big round stone and tried to sling it to the side. Her action, left the drain half covered and her stance, off balance and leaning precariously, vulnerable to the mighty tug of the water vacuum. Before she could move out the way, the force of thousands of pounds per square inch, yanked her body down and trapped her over the hole.