THE MAIN PIER was nearly deserted.

“That’s called The Landing,” Hi said. “It’s where the Aggie Gray docks. She must be out now.”

“Should I pull in?” Ben asked.

Hi nodded. “The Landing has the most slips. Maybe Sewee won’t be noticed.”

Ben selected a space and we quickly secured the boat, acting casual, like we had every right to be there. Wooden planks led up to a quaint covered shelter. A neatly painted sign welcomed us to Dewees Island.

“Nice digs,” Hi said.

He was right. Lowcountry marsh stretched in every direction. Pelicans roosted on weathered pilings, wings stretched, basking in the warm afternoon sun. Cranes fished among the reeds and cattails rose from the still water.

“It’s pretty here,” Ben said. “Even if we strike out, it was worth the trip.”

Just off the dock we passed a fleet of golf carts, neatly lined up, waiting to shuttle supplies purchased off-island by homeowners and renters.

Keys dangled from the ignitions of several.

Hi cocked an eyebrow, but I shook my head. Illegally docking Sewee was one thing, swiping a golf cart was quite another.

Hi sighed theatrically. I ignored him.

We proceeded onto a wide road that appeared to be made of white gravel. The drive was well maintained, and broad enough for two carts to pass.

“The limestone!” I crouched and picked up a piece of the paving material, then pulled one of Bonny’s pebbles from my pocket.

My heart sank.

The crushed limestone composing the road was white, grainy, and very sharp edged. Bonny’s pebble was smooth, solid, and drab gray.

“Maybe limestone dulls with age?” Hi suggested hopefully.

“Maybe.” But the two samples looked nothing alike.

Just ahead was a circular three-story building occupying a small peninsula. Out front, a flagpole flew the Stars and Stripes above the South Carolina state flag.

“That’s the admin building,” Hi said. “It also has an educational center, a few science labs, and a post office. That’s about it for Dewees.”

“So where do we start?” Shelton surveyed our surroundings. “I see two paths.”

Hi accessed a map on his iPhone. “Dewees is basically two strips of developed high ground surrounding a large central lagoon. The rest of the island is undisturbed marsh and swamp.”

He pointed to three o’clock. “That path leads across the tidal marsh to the oceanfront properties. The clubhouse is also down there.”

Hi pointed toward twelve o’clock. “Ahead are the other public buildings, the composting plant, the firehouse, and the old church. They border the lagoon.”

“Where would the flytraps have grown?” Ben asked.

Hi shrugged. “I’d put my money on the lagoon. To lure their prey, flytraps need stagnant conditions, with low wind. The swampier, the better.”

“Then let’s head straight,” I said.

“Goose chase,” Shelton muttered, but set off with us.

We followed the road about another thousand feet. To our left stretched acres of open marshland. To our right lay the pond.

“It’s called Old House Lagoon,” Hi said. “It’s the largest body of water on the island. Plenty of gators in there.”

A small, shallow cove appeared just ahead on the right, an offshoot of the main body of water. Its surface was opaque lime-green, dotted here and there with lily pads. A path skirted the cove, leading to a cluster of live oaks where the inlet joined the lagoon proper. “What’s down there?” I asked.

Hi scrolled on his cell before answering. “That’s Old Church Walk. There’s a tiny chapel tucked in the trees by the lagoon’s edge. There’s also a fishing dock.”

I thought for a moment. “When was the church built?”

Shelton beat Hi to the punch. “Early 1700s. I checked online. It’s the oldest structure on Dewees by two centuries.”

“It was here when Bonny escaped her dungeon?”

Shelton nodded. “It’s a marvel. There was nothing else out here. An Irish monk built it, then spent decades trying to convert the local Sewee. He either gave up or died, no one knows. But the building still stands.”

“We need to see it.” I was getting that feeling. Again.

“A destination!” Hi circled a finger in the air, then pointed downhill. “Onward to ye ancient house of worship!”

With that, he cut off onto the trail.

The church was smaller than I expected. A square bell tower formed the front, fifteen feet tall, broken only by a single wooden door at its center. The rectangular chamber behind had a steep slate roof and two rounded windows on each side.

The entire structure was composed of crumbling stone blocks.

Gray stone blocks.

Limestone blocks.

“Wow.” Hi pointed at my pocket. “Check the sample. That has to be a bingo!”

I approached the nearest wall and pulled out the pebble. The pattern and color matched exactly.

“Identical limestone,” I said. “Beside a perfect lagoon for Venus flytraps.”

“Impossible!” Shelton rubbed the back of his head. “No one is this lucky.”

“Seriously.” Ben sounded uneasy. “Hitting paydirt a third straight time? You’re starting to freak me out.”

“This building was here in Anne Bonny’s time.” I ran my hands over the rough-hewn stone. “Built by an Irish monk. Bonny was Irish herself, and obviously very religious. And limestone was very popular with church architects.”

“I’m officially excited,” Hi announced. “If Saint Limestone here has nothing to do with Bonny’s treasure, it has to be the most painful coincidence of all time.”

“I don’t believe in coincidence,” I said automatically.

“We know.” Jinx.

“I take it we’re going inside?” Shelton said.

“Absolutely.” I stepped to the door. To my surprise, it swung inward easily.

We entered a small antechamber with ornate stone fountains jutting from the walls. Ahead, an archway opened into the nave.

Two rows of pews flanked a central aisle that led to a simple stone altar. The one-room chapel was obviously still maintained. The floor was cleanly swept, and unlit candles filled brass sconces lining the side walls. In the far right-hand corner, another door exited the rear of the building.

“They must leave this place unlocked for private worship,” I guessed. “Good thing the locals are so trusting.”

“Sweet Jesus.” Ben was staring straight ahead, eyes wide. “Holy crap.”

“Don’t blaspheme in church!” Shelton whispered. “JC lives in this piece. Bad mojo.”

“What is it?” I followed Ben’s sightline to the rear of the chapel. Scanned. It practically leaped out at me.

My heart threw an extra beat. Then three more for good measure.

“Mother of God,” Hi breathed.

At first glance, the stones of the rear wall seemed uniform in pattern. Careful scrutiny showed that was not the case. White rocks imbedded in the gray limestone formed a pattern.

Five feet tall and three feet across.

A Gaelic cross.

Hi slapped his side. “Tell me that’s a coincidence.”

“Tory, you have psychic powers.” Shelton looked thunderstruck. “I will never doubt you about anything. Anywhere. Anytime.”

Ben just stared.

“Check the cross!” Shelton was already moving. “There might be something hidden behind it!”

We attacked the wall. Tapping. Prodding. Banging fists. Digging with fingernails. At one point Hi yelled “Open Sesame!”

No good. The stones were impervious to our assault.

I dropped my head in frustration.

That’s when I saw it.

Like the walls, the chapel floor was paved with limestone blocks. An irregularity was carved into one of the flagstones at the foot of the cross.

Kneeling, I leaned in close.

The stone was scored with two small lines, one short and horizontal, the other long and vertical. Together the lines formed a crude cross.

With the top arm curving ever so slightly right.

“Here here here!” I squealed. “Bonny’s personal cross! The treasure is under this flagstone!”

“How do we lift it?” Hi was bouncing like a pogo stick. “Who brought the explosives?”

“Wait here!” Ben bolted out the front door.

Minutes passed. Hours? I picked at the stone’s corner, knowing it was useless but unable to stop. Shelton paced, hands locked behind his back. Hi drummed his chest, while staring at the floor and humming “I Gotta Feeling.”

“Open up!”

Ben was outside the chapel’s rear door.

Hi raced over and slid back the bolt. Ben entered gripping a crowbar.

“On the way here we passed a utility shed. I’ll return it when we’re done.” Crooked smile. “Unless I’m carrying too many bags of jewels.”

“Get to it!” Shelton squeaked.

Ben wedged the crowbar between the flagstones and pried. Once. Twice. Three times. With a groan, the block inched upward, then fell back into place.

“Get it done, Hercules!” Hi pumped both fists. “You da man!”

Ben planted his feet, jammed the crowbar deeper into the newly created gap, and heaved. The stone rose another few inches, dropped.

Jam. Heave. Drop. Jam. Heave. Drop.

Slowly the block yielded. With one final thrust, Ben lifted the stone’s underside above floor level. We grabbed the lower edge and helped flip it. The block tumbled to the floor with a thunk.

“It’s a hidey-hole!” I yelped.

We’d exposed a hidden compartment roughly a yard in diameter.

A dusty object rested in its center.!!!Yowza.