I had a plan. I was going to tell Grandad I was doing a project on bats at school and that I wanted to come over and do Bat Watch in his garden. Grandad would have done his jobs for the day and hopefully be ready to put his feet up and take it easy. So I’d be able to have a good look at the tree and have a proper hunt for dragons. And as for Grim – I just had to hope he’d be taking it easy too.

The next evening I arrived at Nana and Grandad’s fully prepared. In true undercover style I’d brought my night-vision goggles, binoculars, clipboard and a book on bats. I was almost beginning to believe in the bat project myself! Of course it nearly backfired when Grandad started reeling off facts about the habits of our native bats and got so into the idea he decided he’d come and join me.

‘Actually I’m supposed to do the project without any help,’ I told him quickly.

‘Don’t worry, I won’t do the work for you, Chipstick. I’ll just watch. Scout’s honour.’

I shifted uncomfortably.

Any other time I’d have loved to be out in the garden with Grandad – we could be worm watching and we’d have a great time. But I couldn’t miss this chance to look for more dragons. So I pulled out the only thing I knew would stop him in his tracks.

‘I think you’d better take it easy, Grandad. You’ve done loads today.’ And then I added, ‘Think about your heart.’

It was such a low blow I winced even saying it. For a second he looked disappointed. Then in true Grandad form he gave me a smile and said, ‘Right you are. Go on then – off you pop so I can get back to Gardener’s World.’

Which of course made me feel ten times worse.

I hunted everywhere for the dragons, peering into and underneath the hedge, braving the nettles and battling the brambles. I’d seen Flicker dart out of sight enough times to know dragons instinctively hid from humans. Still, I’d hoped that with him flitting around in plain sight of me, any dragons would feel reassured enough to let themselves be seen. But despite that, and my best efforts at hunting through the undergrowth, there was no sign.

Flicker settled on my shoulder and sneezed a glittering spray of sparks.

‘This is hopeless,’ I moaned, nursing a scratch. ‘There’s nothing here. Am I wrong about this, Flicker? Are you the only dragon?’

He flew up and ducked behind me. Eagerly I spun round, hoping he was trying to show me something. He was. It was my smouldering bum. One of his sparks had landed on the seat of my trousers and was smoking! I batted at my backside.

I sighed. Maybe I was looking in the wrong place. After all, it was Grim’s garden that had been messed up.

I turned and looked at Grim’s vegetable patch and at the little lean-to greenhouse that was attached to his shed, full of tempting greenery. A new polytunnel was lying in pieces, the plastic shredded and the seedlings it had been covering scattered far and wide. Surely this was proof there had to be more of them? Unless Grim was right and it was just vandals.

‘I need to have a closer look,’ I whispered to Flicker. I wasn’t sure why I kept telling him stuff when he was only interested in demolishing Grandad’s lettuces, but I had to talk to someone.

Before I could change my mind I stepped over the little wire fence that separated the two gardens. For a second I had a feeling that I was being watched. I stood frozen, listening to the breeze rustling the leaves on the hedge that bordered the fields. In my mind I could picture all sorts of things lurking behind there, but now really wasn’t the time to let my imagination run wild. I reined it in and reminded myself that the scariest thing around here was probably Grim.

I looked around, scanning the garden up to the dark house where he lived. There was no sign of him, not even any lights on. If I was lucky, maybe he’d gone out for the evening.

Flicker fluttered over to join me. He settled on another plant with huge leaves and started nibbling at it. I made my way further into the garden, hoping my luck would hold.

It didn’t.