Grady, Will and I explored every inch of the beacon. Lizzie even pressed her thumb against any spots on the rock that looked smooth, but nothing happened.

Carmen rose and started to walk slowly around the concrete base, looking at the ground. Then she widened her circle. She stopped about ten metres out, the wind whipping her hair like dark flames. She called something, but the wind stole her words.

I stood, holding on to the beacon. “What was that?”

“Behind this stone,” Carmen croaked as she clutched her arm against her chest. “There’s a plaque.”

We raced to join her, fighting the dragging wind.

When we reached her, Carmen crouched and pointed. There was a low stone with a commemorative plate attached. It told us the beacon had been erected during the Napoleonic Wars.

“If the beacon is that old,” Grady said, “are you sure it’s hollow?”

“It’s hollow.” Will touched the screws on the plaque. “And these seem new. Anyone got a screwdriver?”

I passed over my Swiss army knife and he got to work. The rest of us stood shivering around him, the wind tearing at us angrily.

Finally the screws dropped out and Will lifted the plaque. Beneath it was a familiar screen.

Lizzie looked at us.

“Do it,” I said.

She kneeled and pressed her thumb to the sensor. The screen lit up.

Her fingers hovered over the keypad. “All right, you guys, what was the answer to the riddle?”

I looked at Will and he blinked. “I haven’t even thought about it.” He looked shocked. “I completely forgot.”

Lizzie looked up. “How much time do we have before they catch up?” She gestured back towards the grove.

“Not long now.” I shifted from foot to foot. “What was the riddle?”

“I wrote it down.” Grady licked his lips.

Lizzie stared. “Tell me we didn’t leave the book in the rucksacks … down there.”

Grady nodded, his face pale.

“OK.” I swallowed. “OK … we just have to try and remember what it was.” I looked at Will and Grady. “Between us, we should be able to. Didn’t it start with something about being hurt?”

“We hurt without moving,” Will said faintly.

“Yes,” Grady brightened. “Now I remember. Then it was, We poison without touching.”

“Didn’t it finish, We are not to be judged by our size?” I asked. “I remember because it made me think about the girls.”

“Yes, but something’s missing.” Will frowned. “It doesn’t scan. It needs something that rhymes with size.”

“Eyes,” Lizzie suggested. “Cries. Dies?”

I rubbed my temples. “I don’t know, I can’t—”

“Thanks for leaving the ropes for us!” The yell shuddered up the cliff.

I jerked and met Lizzie’s eyes.

“How did we forget to cut the ropes?” she cried.

“You’re in tro-o-o-uble,” came a higher male voice, singing.

Grady pressed his palms against his eyes. “I didn’t think!”

“Neither did we.” Will had caught hold of Carmen, whose face had turned phantom-white.

“We’re co-o-o-oming!”

“What do we do?” Sweat had broken out on Grady’s forehead. “There’s nowhere to hide up here! We’re trapped.”

Will’s eyes were flickering, considering scenarios and rejecting them.

I closed my fingers around my axe.

“We can’t take them on.” Lizzie’s wild eyes met mine. “Car can’t fight – we’re outnumbered.”

“We could climb down the other side and head for the plane.”

“We haven’t got the ropes,” Lizzie said.

“But we’re so close,” Grady wailed. “There’s no one else even here. We started last and we’ve beaten everyone to the final checkpoint. It’s not fair!”

Grady slumped. I put my arm around Lizzie and leaned my face against her hair.

Suddenly Grady straightened. “Hey!” He looked at the cliff and his eyes hardened. “We’ve been so scared, we forgot something.”

“What?” Carmen turned her tear-stained face towards him.

“That team is dangling about fifteen metres above the ground.” Grady showed his teeth. “Right now, they’re the vulnerable ones.”

Carmen’s eyes widened. “He’s right.”

“I’m not dropping anyone off a cliff.” Lizzie shoved her glasses higher up her nose. “It would be murder.”

“And what would they do to us if they could?” Carmen raised her arm.

“You aren’t dead, Car,” Lizzie said. “Even that bastard Reece didn’t kill you.”

“He might as well have done,” she snarled.

“But he didn’t. Anyway, we’re better than they are … aren’t we?”

“I know what to do.” Will stalked towards the cliff edge. “Follow me.”

Will lay on the clifftop and leaned his body over the edge. I copied him. Grady, Lizzie and Carmen stayed back, holding our legs.

Curtis was about six metres below us. The skinny boy with the sharp eyes was just behind him.

Spread out below were his remaining three teammates – one was climbing properly, wearing real climbing gear, like Lizzie’s, carefully picking out handholds. He was quite a way to the left of the others and higher. The final two were stuck further below, using the ropes secured in the vertical crack, unable to move up further until the next ropes had been freed by Curtis and his skinny mate.

“Hey,” Curtis yelled. “We’re gonna tear you apart!” He narrowed his eyes at me. “You better run.”

“Or not,” Will said calmly.

Curtis stared at Will and then back at the skinny boy climbing below him. He saw what I had seen. Although the two boys looked nothing alike, there was something there, some appalling similarity between the two.

“You see, we’re at the top.” Will smiled horribly. “And you’re not. In fact, it wouldn’t take much effort to push you off that cliff. All we have to do is wait till you’re in reach.” He pointed at me. “See Ben’s axe?”

I pulled it from my belt and brandished it over the edge.

“That’s for your fingers.”

“You’re bluffing!” But Curtis had stopped climbing.

“Curtis, whatcha doin’? Get up there and sort ’em out!”

“Shut up, Ryan.” Curtis didn’t even turn his head. He kept his eyes fixed on Will. His Adam’s apple moved up and down. “Maybe we can make a deal.”

“Maybe.” Will shrugged. “But we’ve got all the cards here – right, Ben?”

I nodded.

Curtis winced. “What was in the box you tossed?” He licked his lips. “Tell us. We’ll go back and finish that geocache. When we get back here, you’ll be done, right? And we could still finish the course in a faster time than you.”

“That means you’ll hurt someone else!” Carmen shrieked. “We’re not telling you anything.”

Curtis frowned.

“Yeah, as you can hear…” Will spread his hands helplessly. “We aren’t the ones in charge, so there’s no point in arguing.”

“You want us to just … back off?” Curtis was red-faced now, his shoulders trembling with his own weight.

Will leaned further out. “We’ve got rocks here to drop on you,” he lied. “But we haven’t. Not yet.”

“Why not? What do you want?” It wasn’t Curtis who spoke this time, but the boy behind him.

“We haven’t been completing the geocaches – not since another team stole our first one.”

Was it me, or did Curtis flinch a little at that? I frowned. Will went on.

“So here we are at the end of the course, but we’re going to need your stash to win.”

Grady’s hands tightened on my legs.

“Ain’t gonna happen, you chancer,” the big lad called from below. “Just eff off.”

“Sticks and stones may break my bones,” Grady yelled. “You want a rock dropped on your head?” He was almost breathless with glee.

“Just hang on a minute.” Curtis called quickly. “We were only joking before, right?” He gave a shaky laugh. “I mean, we’re all on this island together. Maybe we could … team up? I mean, you’ve got there first, obviously. I get it. But we’ve got the geocaches. You know what we need for the one in the loch. We don’t. We could work together. Get the money, divvy it up fairly. Fifty–fifty. Half a mil each – that ain’t so bad.”

“That—”

“Shut up, Ben.” Will didn’t even look at me. He shouted down to Curtis again. “What’s to stop you from going back on the deal once we’ve told you what the geochache was? And which of us gives up the body part? You? I don’t think you’d be up for that, mate.”

“We could set up an ambush – there’ll be other teams coming,” the skinny boy murmured.

“You already heard the boss’s view on that one,” Will called with a sigh. “We’re helpless, really. I do think the best way is for you to climb up here, pass us your geocaches and then be on your way – back down, obviously.”

I looked up as a great skua cried out and wheeled overhead.

Abruptly the wind changed and brought with it the sounds of waves smashing on rocks. I looked back down. Curtis was flushed with fury and frustration. “The thing is,” he called finally, “I’m not carrying our geocaches. Max has them.”

“That true?” Will asked.

“Show ’em,” Curtis shouted.

“It’s a bad idea, Curt.”

“Show ’em, Max.”

Max rolled, so that he was holding on to the rope with one hand, then he reached behind him and opened the top of his rucksack. On the top, I could clearly see bloody T-shirts wrapped around misshapen lumps and, tucked to one side, Lizzie’s familiar floral glasses cloth.

“Pass the rucksack up the line,” Will said calmly as blood beat in my ears.

“Ain’t happenin’,” Max shouted. “Bloody cheats.”

The skinny boy looked down. He spoke in such a quiet voice that I could barely hear it, but Max paled and did as he was told. Contorting himself as he dangled from the rope, he pulled off his rucksack.

“Good,” the boy said. “Now drop it.”

“No!” Grady almost lurched off the cliff.

I watched, throat tight, as the pack dropped like a boulder and then bounced at the bottom, its grisly contents spilling out on to the slope.

Carmen’s hand lay half in and half out of the bag, fingers curled up to the sky.

The great skua cawed and dived, heading for the unexpected bounty.

“Get away!” Max started to abseil, waving his arms frantically.

The skinny boy looked back up at us, his eyes sparkling. “Your move,” he said to Will.

Behind me Carmen was whispering over and over again, “Sticks and stones may break my bones, break my bones, break my bones…” until her words were one with the wind and a chill ran down my spine.

Then I saw her out of the corner of my eye as she stood up.

“Where are you going, Car?” Lizzie called.

Carmen looked back at us, her dark eyes almost black. “…but words will never hurt me,” was all she said. Then she lurched away.

I couldn’t worry about Carmen right now. She was safe enough up here on top of the world.

“So, what’s it gonna be?” Curtis tried to sound nonchalant. “You aren’t getting our cache.”

“We can see that.” Will ground his teeth. “And you aren’t getting up here.”

“But you’ll let us climb back down, no dropping rocks?”

Will nodded. Curtis made a gesture and his other teammates started moving down towards the dropped rucksack and the safety of the ground, escaping Will’s make-believe rocks and my ready axe.

Then I stiffened. “Words will never hurt me,” I hissed. “Words. Lizzie – Carmen worked out the riddle! She’s gone to open the last checkpoint box.”

As I rolled to sit up, shifting her from my legs, there was a blood-chilling scream from beyond the beacon. I jolted to my feet with ice in my veins.

Will rolled sideways and got up in one swift movement. Then we were running for Carmen, sprinting against the wind.

She wasn’t alone. Carmen was standing just in front of the checkpoint, with her arms behind her back. Stalking towards her with a twisted expression of joy on his face was an enormous lad wearing full army camouflage, complete with stripes across his face – green, red and brown.

He grinned. His teeth were big and yellow – smoker’s teeth. His eyes, also yellow-tinged and slightly bloodshot, were pale blue and humourless, despite his wide smile. Behind him four other big lads were rising from the other side of the cliff.

They hadn’t been going west when we’d seen them, they’d been going around.

“Spare Parts!” he exclaimed. “So glad we found you.”