All around us are the chirruping of birds and friendly, papery rustlings of the leaves. As usual, birds are landing on nearby branches and shuffling closer to me. Currawongs, wrens, a white cockatoo. The sunlight glows red behind my closed eyelids. Are you there, Mum?

‘I think I can hear the sap rising up the tree,’ whispers Kit. ‘It’s a bit like a gurgling stomach.’

I hear a faint swishing. Is that the rising sap? My ear gets warmer and warmer and the swishing turns to a kind of moan, a bit like the sound of wind whistling around tent ropes. Did Sylvie hear something like this up at Flat Rock when she said the tree was groaning?

My whole body is heating up now, and I know with absolutely certainty that this tree is a being and knows I’m here. I’m sorry I killed your sister, I say inside my head as hot, guilty tears press at my eyelids.

The tree-noise grows louder. I hear a word. It’s not English, it’s nothing like English, but I know what it means. There’s an exhilarating whooshing and buzzing under my skin, the same as I felt up at the rock.

‘The tree’s saying courage,’ I say, and open my eyes.

‘Why courage?’ asks Kit.

‘Not sure.’ But I’m pretty sure he’s thinking the same as me: is the tree offering me courage for a frightening journey in a parallel universe? Or courage for a life ahead without my mum? I don’t want courage. I want reassurance that Mum’s okay, and that I’ll be bringing her back.

I listen for the tree again but all I hear are small, squeaky voices saying, Hurry, hurry, hurry. They seem to be coming from a line of ants crawling up the bark.

Is that you, ants? I think. I’m listening.

In an instant, my head is flooded with a chorus of whispers and grumbles and chirrups. A rainbowcoloured parrot barrels past, shouting, ‘Rain is coming. Rain is coming.’

Hello, I think. Hello, birds. Hello, ants. I hear you! I can’t help grinning.

Something below me is screeching and muttering, and moment by moment, the wall of noise grows louder. Sticking fingers in my ears doesn’t help, because it’s inside my head. Is this what Mum and Sylvie have to deal with every day?

‘What’s Vince up to?’ says Kit.

From our perch high in the tree, we can see Vince striding towards Sylvie, who’s sitting outside our van on a blanket. He’s still wearing his gold pants and looks crumpled, as if he didn’t get much sleep.

‘Oh boy,’ I say. ‘We better hear this.’