Page 1 of Hearts on the Line (The Maverick Key #1)

Dr. Nathan Carter

The Atlantic’s dark tide laps against the dive platform with a pulse too calm to be trusted. Although the waters surrounding Maverick Key appear harmless and inviting, I know better.

Twenty feet below the surface lies an underwater cave system—a blue hole.

I discovered it seven months ago, igniting a surge of interest from academic communities eager to capitalize on its potential for significant scientific contribution.

It could take years to secure university funding to map and study the caves, but private investors have wasted no time jumping in to fill the financial gaps.

I accepted one of their offers, stepping into the role of lead marine archaeologist.

Against the boat railing, I take a deep breath, savoring the fresh scents of ozone mixed with brine and aquatic life, allowing my thoughts to wander.

Our research team has mapped the main cavern, but deeper penetration into the caves remains unexplored.

I’ve started those treks on my own, and today, I’ll venture further than what issafe.

The weight of this decision settles deep in my chest. I’ve broken the rules before, sure, but this?

A solo dive into unmapped overhead cave passages defies every safety protocol.

Always dive with a partner. Always take a support team.

The rules exist for good reason. But some people aligned with this project have an agenda, and they’re starting to ask the wrong questions.

My trust has been misplaced, and if I don’t keep my progress secret, I may lose control of the discovery altogether.

So here I am. Alone.

Maddie’s voice echoes in my thoughts—sharp with frustration after I’d told her I was planning to dive solo. It was a mistake to do so since I couldn’t explain all the reasons why.

“Nathan, why are you pushing boundaries? It’s reckless. One day, you might go too far. You’re smarter than that.”

“You’re right. I’m sorry for bringing you into this.”

“Mom and I need you. Whatever’s driving you to do this just isn’t worth it. Please don’t do it.” She struggled with her words, her voice shaky, a sure sign she was holding back her tears. Once they started, she couldn’t stop them. Each of her whimpers was a dagger to my heart.

“Sssh. It’s okay. Please don’t worry. I promise I’ll be careful, and I’ll find another way.” I tried to walk it back—to ease some of the anxiety I’d caused.

“Promise?”

“Yes. I promise.”

Her sobs subsided into a soft, wet sniffle. “Thank you. We love you.”

“You and Mom are everything to me. Get some sleep.”

I imagine her face—eyes focused, mouth set with determination, gripping the phone in her hand.

I lied to her on our call, and the guilt is eating me alive.

She’s sacrificed too much already—finishing medical school and caring for Mom as early-onset dementia claims more of the woman who raised us.

Soon, I may be the only one Maddie has left.

After I complete this project, I’ll ask them to live with me on the island.

I have more than enough space at the inn, and Ms. Connor will help with Mom.

Maddie and I just get each other, and there’s so much more that I can teach her.

I think of our childhood in Sarasota. Playing, growing up, and diving.

My little sidekick until she became her own woman.

Now, I picture her swimming in the ocean again, happy and carefree like she used to be.

She’s going to love Maverick Key.

Sorry, Mads.

I tighten the straps of my rebreather.

One day, I know you’ll understand.

Now, I picture another’s face, and my heart beats faster.

Her gentle smile disarms me in ways I never expected.

I’d rested my hand on her stomach after we made love last night, trying to memorize the softness of her skin and the measure of her breaths.

Every risk I take now isn’t mine. It’s ours.

The promise of our future is heavier than the gear on my back.

It’s not fear making it heavier—it’s hope.

I shake off my memories and check the readings on my dive monitor. There isn’t any room for mistakes or distractions on this dive.

The rebreather will recycle my exhaled air, scrubbing out carbon dioxide and replenishing oxygen. The closed circuit allows much deeper, longer dives than traditional open circuit scuba diving but demands vigilance. Malfunctions are often deadly.

I signal to the captain and roll backward off the dive platform.

Cold water hugs me in an icy embrace. At ten feet, sunlight still filters through the water.

Parrot fish dart around me, flashing blue and yellow at the edge of my vision.

At fifteen feet, I approach the outcropping of coral and an oasis of life.

At twenty feet, the world darkens, and the coral fades into a center of barren sand and jagged rock.

The blue hole.

My pulse quickens. Eels, sponges, starfish, and barnacles circle the entrance’s edges, opening like a portal into another world.

I swim in, cutting through the cobalt-blue water as the temperature drops.

My flashlight illuminates the limestone walls peppered with striations and veins of quartz.

The waters inside the hole are beautiful but empty, as if life doesn’t dare linger here long.

Stalactites hang from the ceiling, formed over thousands of years by dripping water, above ground, then flooded into giant sinkholes under the sea. My dive light reflects off their surfaces, casting an eerie menagerie of dancing shadows.

But the real mystery lies deeper.

There are seven tunnels of various shapes and sizes that branch from the main entrance.

One of the narrower passages looms ahead, a jagged throat carved into the limestone wall.

I find the nylon permanent dive line I’d laid during my prior dives.

Tightly tucking in my arms, I adjust my position and angle my body, gliding forward with small, controlled kicks.

My fins don’t stir the water. One kicked-up cloud of silt could blind me.

The passage narrows, walls of rock grazing my suit.

I exhale slowly, deflating my chest to slip through a pinch point barely wider than my shoulders.

The tightness of the space presses in from all sides.

Each breath I take is deliberate and loud in the silence.

I take a left and push my limits even further, navigating through an unbelievably narrow vertical shaft.

The tunnel shifts abruptly, its narrow clutch forcing me to inch through sideways.

The loud grating of my tanks against the rock echoes against the walls.

Entering another cavern pocked with over a dozen more tunnels, I follow the path I charted on my last dive, entering the corridor.

When I reach the end of the existing line, I unspool more, carefully securing and tightening it every few feet.

I’m now in unexplored territory. Unsure if this path will close off, I push forward.

Then, the passage opens.

I float into a massive open chamber and adjust my light. Sweeping the beam over the floor, I catch my breath.

Half-buried in the silt is a ceramic shard. I pick it up and gently wipe it clean. Intricate patterns emerge, delicate carvings untouched by time. My breath fogs my mask as I scan more of the chamber. Another object, this one with a beautiful patina. Platinum? A tool or weapon?

My chest tightens as recognition of the objects sinks in.

After years of research and fighting my skeptics, and now, here it is. Proof.

Excitement surges through my body as I catalog each item, keeping my movements steady. But this is more than a breakthrough—it’s now a target. He will try to take this discovery and twist it into greed. This is just the beginning of a larger journey. I have to keep it safe.

The red glow from my monitor pulls my attention back to the dive. I’ve stayed too long. The rule of thirds dictates using a third of your gas to go in and a third to get back, leaving what’s left as a reserve to account for the unexpected. My gauge reads 40 percent.

I pack my tools. I’ll need a proper team to procure these artifacts once I’m sure I can keep them safe. I begin my return, following the line with steady movements. The moment I prepare to enter the transition chamber, the rebreather hisses, followed by the terrible vibration of the alarm.

My stomach drops as I check the system. Every muscle in my body tenses. The scrubber canister has stopped working. Switching to the bailout, I take a slow breath.

Nothing.

This isn’t an accident. Panic claws at my heart, but I push it away.

I only have enough air left for a few more deep breaths.

I keep my tanks, but drop all the other gear.

Kicking harder, my lungs burn as I push through the pinch points to reach the exit.

I take my last breath as I enter the main cavern.

When I emerge from the exit, the faint glow of the surface is in sight.

But there’s no air left, and it’s too far away.

She smiles, her soft voice whispering in my mind—a siren’s call. Stay with me. Don’t leave me. It’s beautiful here. The call to stay, to embrace the peace of the deep, is strong.

But I’ve made promises to those I love, and I won’t let myself give up.

With every ounce of strength I have left, I push upward—toward the light. Darkness closes in, and my vision tunnels. I exhale.

Forgive me.