Torun’s heart would not calm.

Lucy swam in front of him. Her electric light cast a meager glow swallowed by the large, winding cave neck. Even though she was unharmed, he replayed the scene outside the cave.

The deadly cave guardian rose from the depths. Lucy did not show the Sea Opal. The cave guardian stroked and tasted her fearlessness.

Why did she not bring out the gem? The cave guardian must have tasted the Sea Opal on her body. Otherwise… Her crushed, mangled mass would give a metallic taste to his nightmares.

Lucy tapped a device on her wrist and pointed to the surface. She wanted to rise.

He gestured for her to continue on. Half the cave complex remained.

She recovered her second grease pencil, cleaned her board, and wrote inscrutable symbols. He guessed the meaning from her body language. She worried about her air. Back on the trawler, she’d performed complex calculations with Gracie before wrapping herself in plastic-encased bubbles and entering the water.

“You are almost at the cavern,” he assured her. “There is air for you to breathe. You will not need this portable supply once you have drunk the elixir and transformed.”

Inside the air bubble in her face mask, her brows furrowed. She underlined symbols.

“Trust me.” He stroked her cheek. Cool and smooth. “I promise, upon the honor of my castle, you will be well.”

She shifted the black circular device in her mouth. Bubbles flurried out with every breath. They tickled him where they touched.

This was why cave guardian had played with her. Air-breathing humans were so interesting. And so ticklish.

He arced over her and drifted down the cave. “The sooner we arrive at the cavern, the sooner you will feel reassured.”

“Waghlaghl,” she said, attempting to speak normally.

The water medium terribly distorted her words. Still, wasn’t she saying his name with disbelief?

“Come, Lucy.” He floated at the edge of her flashlight. “Do not fear the water.”

She wrinkled her nose, breaking the seal of her mask and losing bubbles. Seawater sloshed in.

Lucy sighed, pressed one edge of the mask, and blew even more bubbles. The air returned to the mask full and clear. She grimaced at him as though that were his fault and followed him deeper after all.

He had to convince her twice more to continue, and she whimpered with anxiety by the time they finally reached the open-air cavern.

Uncounted millennia ago, the seas had been lower and this cavern had existed above the ground. When the island shifted and the seas rose up again, this small bubble became trapped. Many atoll caves contained bubbles. Their isolation gave mer an opportunity to practice land walking and air breathing unseen.

Lucy floated to the ledge. She removed the black tube from her mouth. “This is amazing! I’m sorry I doubted you. Help me up.”

He assisted her staggering from the water. She unclipped the heavy belt of weights from her waist, wriggled out of her heavy air tank, and unsnapped her inflated vest. Beneath the surroundings of artificial air, she wore a skin-tight, short-sleeved dive suit in pink and blue stripes.

She ran a ticklish finger down his spine to the bare buttocks.

He swayed toward her. “Yes?”

She backed up a step, reddening. “Nothing. I mean, where are your gills, mister merman? I didn’t see them underwater.”

“You will see more after you transform.”

“Right.” Her flashlight strained to the distant ceiling. Her words echoed in the cavern. “So where is the magic potion?”

“The elixir is this way.” He led her across the rocky floor. His feet changed shape, returning to a compact human foot, to more easily grip the uneven surface.

“This is a pretty good place to hide it. You don’t have to worry about thieves breaking in.” She stumbled after him. “Our return will have to be more direct. I’m on fumes. No dawdling with giant octopi on the way out.”

“Yes, I hope the cave guardian is satisfied by your right to be here. She tasted you thoroughly.”

“Tasted?”

“Cave guardians taste with their skin and their suckers. She touched you all over, so she knows everything about you.”

“Like my brand of sunscreen?”

“And what you ate, where you slept, and your likes and dislikes. You communicate many things through your skin. Taste is how cave guardians come to know us, and each other.”

“So a hug is like a hello.” She made a noise. “The octopus is a she? I was going to name her Mr. Huggles.”

“I am sure you may name her as you wish. Her name is untranslatable for our tongue, certainly.”

Lucy shivered.

“Are you afraid?”

“No. It’s cold in here. Aren’t you cold?”

“I do not feel cold.”

“Hey.” She focused her light on an ancient column. A face and hands made shadows. “This almost looks like a carving.”

“It was a church. A sacred church on a sacred island.”

Her mouth opened. She touched the stone reverently, awed. “There was more than one?”

“So many, they scattered across the sea. Our cities also used to be closer to the surface. In that ancient time, we had as many females as males.”

She removed her hand and struggled to laugh. “You know, when I’m in a mystical place like this, I almost believe everything you say is literally true.”

“It is.”

“I mean, that it’s not just a mistranslation by our language barrier, or culture, or something.” She climbed up the smooth-worn steps to the dais.

“It is the truth.” He stood before the weathered offering bowl. “Drink.”

She peered into the depths. Her flashlight washed out the natural iridescence of a hundred thousand years of liqueur steeped in the Life Tree Sea Opals. “This is the elixir?”

“Diluted. It will create a temporary transformation.”

She hesitated.

“What is the problem?”

“I was imagining a future conversation with my doctor. As in, ‘Well, doctor, I was feeling fine until I followed a mysterious tribal warrior into an undersea cave and drank from a pool of stagnant water.’”

“It is not stagnant,” he said.

“It’s brackish.” She disturbed the dust, revealing the jewels. Her jaw dropped. “Are those Sea Opals?”

“Yes.”

“There’s enough here for a hundred yachts! A thousand!”

“Please do not gather these,” he said, stopping her from fumbling for her bag. “You will collect unclaimed gems in my village. These opals belong to the brides of the past.”

She closed her bag as he asked, and shivered again, harder. “Now I really have made the pool brackish.”

“Turn off your light.”

She did. Beneath the swirling dust, the pool shimmered with the pale opalescence of the still potent jewels piled in its depths.

“Now do you see?”

She didn’t answer.

A new, small light appeared. Her cell phone.

“There’s no signal,” she told the camera, “and I can’t see a darned thing, and also it’s freezing, but I wanted some documentation of this,” she shot the pool with the phone flash, “in case someone has to recover my body. I am drinking this cold, brackish water from a pool filled with Sea Opals so that I can gain the power of mermen and travel to Torun’s undersea village, where he says there are ‘many more’ Sea Opals than here. Ready? Elyssa, Mel, here we go.”

Lucy scooped up a handful of water and slurped it for her camera.

His belly tensed.

Although he had imagined a bride joining him like this a thousand times, now that the moment had arrived, her actions were both more practical and more worrying than he had imagined.

Would the temporary elixir work on her? Was there something special about the brides of the sacred island? Could this mainland woman from a country called Oregon also not transform?

Her soul must resonate and activate the Sea Opal-infused elixir. Would it do so? Had she bonded to Torun deeply enough?

She must.

Lucy was a special human. She possessed the capacity for great brightness, more than any other woman. Her soul shone steadily since she left the trawler and entered the water, proving her connectedness to the ocean. She had flared brighter yet with her introduction to the cave guardian, and it had allowed her to pass.

Now came the true test.

Was her soul resonating enough with his to transform her to accept the sea?

She swished the liquid around in her mouth and swallowed. “Not bad. A little salty, which is what you’d expect, but also there’s another flavor. It’s not sweet, not bitter. Maybe savory? A bit umami.”

“How do you feel?” The words were tight in his throat.

“I don’t know. Normal, I guess.” She swirled her hand in the water. Iridescence twinkled. “How long does it take?”

He had never attended this ceremony. No mer had. The brides had already completed the transformation before they entered the water. He remembered their arrivals much later, escorted by honor guard into the city, from his childhood.

“What signs should I look for?” she asked.

“You will be able to swim better and see without your flashlight. Come, let us test it in the water.”

Her toe stubbed against an outcropping, and she swore. “Forget seeing without the flashlight.”

“Try in the water, without the air bubble on your face.”

She knelt on the ledge, set up her cell phone, and started another recording. “In the interest of science, here is the first test of the fabled mermaid elixir.”

Lucy held her breath and dunked her face in the water.

He slipped in, darted beneath her, and looked up.

She had her eyes closed.

He tickled her nose and spoke to her under the water. The words vibrated in his chest. “You will never see anything that way.”

She wrinkled her nose, eyes still closed, and lifted her head out. He bobbed to the surface beside her.

“I’ll never see anything with my eyes open, either.” She wiped her face.

“Come all the way in.”

“I should have brought my snorkel.”

“Come.” He rested his hands on her knees. “Take off your suit. Leave the surface world behind. Take a deep breath beneath the ocean and immerse yourself in your destiny.”

She squinted. “And don’t choke when ‘my destiny’ pours into my lungs?”

“Believe, Lucy. Your body changes at your will. You must will it.”

Her soul diminished. She hugged herself. “You don’t always get what you want. It doesn’t matter how badly you want it.”

“Breathing underwater is as natural as losing yourself in your true love’s kiss.”

She stared across the pitch-black cave pool. Her fingers stroked his hair, slivering through his wet locks. She no longer shivered, and her skin smoothed. Her fingers did not wrinkle.

“Maybe I’m over-thinking it,” she murmured and focused on him. “I’m afraid.”

His gut clenched. “I thought you were not afraid of the water.”

“I’m afraid of you.”

Him? No, impossible. He misunderstood. “Me?”

She soothed his cheek with her firm fingertips. Sadness touched her lips. “What will you do when I transform, we go to your village, and the Life Tree doesn’t heal me?”

“The Life Tree is more powerful than you can imagine.”

“What if it isn’t?” She burned with the intensity of her question. “Will you leave me for another woman? Or will you stay with me no matter what happens?”