A tiny piece of paper comes out with the cork stopper. It is intricately folded, like a miniature origami. With great care I open it. My fingers feel so big and clumsy.

There’s a drawing on the paper. When I look at it through my magnifying glass, I see that it’s a plan of a house. Is this the key Grandpa Truegood was talking about? But where is this house? And what am I supposed to do now?

‘I need your help again, Grandpa Truegood,’ I say, sending my mind to Gold Leaf Lodge. I concentrate hard like I did in the car. But no matter how hard I try, there seems to be something blocking me.

I need Petal’s brains and Big Bobby’s genius with plans and paper. They might have some ideas. It’ll be like old times. Then, like a cold shock, I remember: Petal’s hanging around with Stella now. At school she was wearing her hair piled on top of her head like a true Stellagtight. I could hardly believe it. And she’s barely spoken to me in the last week. That leaves only Big Bobby.

I call out goodnight to Momma so she doesn’t come in later and find me gone. Then, raincoat hood up and the jade bottle safely tucked away in my pocket, I quietly climb out the window with Mystic at my heels.

The wind is still gusting fiercely, blowing twigs and leaves and rubbish about. It’s no use riding my bike in this gale, so I walk, leaning into the wind and biting rain. Mystic is excited being out so late on an adventure – he yelps his delight and runs ahead, splashing through the puddles on the road.

There’s nobody about on the streets as I pass through town. Just one lone light in the funeral parlour. What is Mr Maloney working on so late?

I suddenly remember that tomorrow is my birthday. I feel a prickle at the back of my neck as a memory of the nightmare surfaces: a silver beast clawing and pushing me down, bubbles, red water. But why would Kalila drown me? She and Raffi are my friends. I hunch my shoulders as I taste that strange voice in my head, the one that made me set the trap. But this time I know what it is. This time I know it’s the jinn I must fight, not Kalila. I force the voice away. The only thing I need to do now is to concentrate on deciphering this drawing.

Take one step at a time, Ziggy, I tell myself.

Big Bobby Little lives above his parents’ grocery store. His room is upstairs around the back. I can hear country music blaring, even though his window is closed. I throw a pebble against the glass. Then another.

Finally, the music is turned down and Big Bobby looks out. I beckon for him to come down.

In the beam of the flashlight under the back porch, Big Bobby inspects the drawing with my magnifying glass. He turns it to the right, then to the left, then upside down. He turns it over and holds the flashlight behind so he can see the drawing backwards. He considers it for a long time.

Pulling out his notepad, he writes one word. School.

‘Dell Hollow Elementary?’ I say.

He nods. See here? He points to one of the rooms with his pen. This tiny room is off the library. I’ve never seen it before. You?

I shake my head.

It could be a storeroom that nobody uses. But it’s worth checking out.

When we get to school, there’s a dim light over the front entrance. The rest of the building is in darkness. I’m glad Big Bobby is with me. Schools without kids are sad places. It’s the laughter that makes them happy. And at night they are just plain scary.

The town clock strikes ten as we go around the side of the building to the cellar window. Big Bobby slips his penknife in to loosen it, like he did the other morning, and we climb through.

The first thing we do is take off our raincoats. Mystic shakes himself, sending a fine spray around the room. We also remove our sodden shoes. We don’t want to leave telltale puddles.

We walk down the passage that goes to the kitchen and dining room. Then we make our way to the front of the school where Principal Poole’s office, the administration office, the ballroom and the library are.

In the library, Big Bobby looks at the drawing. He points with his flashlight at the middle bookshelf.

We begin taking out books. They seem to be the heaviest and biggest books in the whole library. I wonder if this was deliberate. A rat the size of a kitten jumps from the shelf onto the floor and runs between my legs, making me cry out. It scurries across the carpet with Mystic in pursuit. Big Bobby chuckles silently and I elbow him in the ribs. We take out more books, looking for a door to the hidden room. Eventually, the bookshelf is empty.

‘It has to be here,’ I say, feeling exasperated and disappointed.

The bookshelf is solid wood and too heavy to move, so Big Bobby reaches through and starts tapping the wall behind the empty bookshelf with his flashlight.

It makes a hollow sound in one place and a dull thudding in another.

‘The door’s been plastered over!’ I say.

I look around for something heavy. On the librarian’s desk is a bronze bust of Principal Poole. Big Bobby catches my thought and smiles. He picks up the bust and, with a single blow, makes a hole in the plaster.

A rush of stale air hits us and I hear a small sigh come from the hidden room as if it’s happy to breathe fresh air at last.

Big Bobby makes the hole big enough for us to shine our flashlights inside. The musty smell of old books is what I notice first. Then my eyes grow wide with surprise.