He walks to the window and peers out.

‘We’re so high up,’ he comments, looking back at Karl and me. He grins. ‘Can a kangaroo jump higher than a house?’

Karl rolls his eyes. ‘Not one of your awful jokes.’

‘No, a kangaroo can’t jump higher than a house,’ I say, thinking of our tall roof.

‘Of course it can,’ Walter exclaims. ‘A house can’t jump!’

Karl groans, but I giggle and Walter gives me a wink. He looks out of the window again.

‘You can see all the way to Rosental from here,’ he says. ‘Ouch!’ He whips his hand from where he’d rested it on the sill and shakes it, then examines his finger.

I jump up. ‘Let me see.’ The dark line of a splinter slices diagonally into the soft padding at the top of Walter’s index finger. It’s in too deep to pull out without a tool. ‘I’ll get my tweezers.’

Hurrying down the ladder I hear Karl laughing. ‘Watch out, she’ll be amputating that. She has some ludicrous dream of being a surgeon…’

I grab my kitbag from my room. Back when we lived in the flat and I roamed the streets with Tomas, I’d bring my medical kit, slung on my back, and keep an eye out for injured creatures which might need help. The odd stray dog, which Tomas would hold still (getting bitten once or twice) while I treated patches of mange with borax; next-door’s cat with an injured tail that I bandaged, much to its disgust. I once even tried to glue the legs of a daddy-long-legs back on, but it died anyway.

I run back to the treehouse and carefully pull the splinter out of Walter’s finger with my tweezers, then I give the hole a squeeze and it bleeds, so I know all the wood is out. Dabbing the wound with iodine, I tell him not to get it dirty to avoid infection.

Karl has spread a blanket on the floor and lies on his side, propped up on one elbow.

‘She even reads books on medicine,’ he comments, watching me. ‘So dull.’

‘They are not.’

‘Anyway,’ Karl sighs, ‘you do know, women can’t even be doctors now?’

‘That’s not true!’

‘Ask Vati if you don’t believe me. However much you don’t like it, Hetty, you’re a girl, and you should start behaving like one.’

His tone is not unkind, but I burn hot as I pack away the iodine bottle and close my kitbag. I feel the boys’ eyes watching me as I fumble with the straps and buckles. Women can’t even be doctors. Is he right? A hole opens inside me.

‘Well, thank you, Dr Heinrich,’ Walter says into the silence, ‘nothing wrong with holding onto a dream.’ His words soothe like ointment on a wound. He winks at me for a second time. ‘I should pay you for your trouble,’ he continues, furrowing around in the paper bag and pulling out a large piece of caramel.