Fraser pulled a slim torch from the pocket of his jeans.

‘So that’s what that was,’ I said with a killer smile, and opened the gate.

The tunnel was just a few metres long before it turned a corner. Metal frames held the roof up, with older wooden struts in between. It looked sturdy. Sort of.

‘Turn left.’ Fraser’s voice, and Tyger’s bark eddying around it. ‘You don’t have to go far.’

My mouth had a chemical dryness to it and matches were being struck in my stomach. Should have eaten more at lunch.

I couldn’t see any minerals. I’d been expecting a treasure chest of blinding, sparkly rocks, an adventure playground for a Russian oligarch’s wife. But it was just stone, black and damp, with a smell that made me think of changing for gym in Year 8 after lunchtime in the rain. No bling at all.

The tunnel narrowed. Fraser called my name and the sound splintered. God, I was scared. The whole thing could come down on me and I’d have my own rubble coffin. There’d be a memorial service on the hill, Fraser’s head bowed, Tyger in a bow-tie, Stef with my name freshly tattooed on his neck, Lottie weeping in the drizzle, Dad holding Benji’s hand, explaining quietly that Polly wasn’t here any more while Benji did his elephant-stamp into the ground. Maybe it would be karma. I deserved it, after what I’d done.

There was a tiny, dripping sound, the pock of a serene table tennis match. I stopped to listen, the dark shrinking around me. I held my breath and the drips seemed to stop and that was more scary than anything. I turned to hightail it out of there, and a hollow caught my eye. An opening.

Oh, fuck it. Two fingers to the funeral. It was just rock.

The archway opened out into a cave. This felt different. Warmer, somehow, even though my cheeks were clammy. My torch spread pale butter on the walls. On one side there was a curved lip of rock, cool and smooth, perfect for sitting on, and marks scratched on the wall, nothing you could really read. I felt like I’d disturbed something – like people had been hanging out here and had scarpered when they’d heard my boots tramping down. Shreds of their shadows, their smells, lingering in the air.

The light caught a small shape above my head. A dark, solid object tied to a thin pole by a ribbon that had maybe once been red. I could have cupped it in my hands. Standing on tiptoes, I tapped it with my fingernail. A quiet, metallic clank. It looked very old.

A heart.

‘Thought you’d fallen down a hole.’

A lung-smash of fear and relief all at once. ‘Jesus fucking – Fraser.’

He was looking around, the vodka bottle dangling from his fingers. ‘Not been in here before.’

‘How long’s this place been here again?’ I asked, taking the bottle off him and having a massive, panic attack-soothing swig.