‘“What?”

‘“An Egg.”

‘“An egg?”

‘“It was my only child, just ready to be born. It was snatched from my nest a thousand years ago by the Tylwyth Teg. I was a white swan then, generous and kind. Now I wear black as my mourning robe.” She dipped her neck gracefully. “And I am no longer kind.”

‘I felt quite excited. This would save my life. “I’ll find it for you! Just let me go and…”

“You have no idea what it would cost you to find. But this is what I’ll do. I will let you live, but you’ll live as a bird. And the spell will only be broken if you bring me what I want.”

‘Before I could even jump away, it had pecked my hand with its beak. A cold, icy pain went through me. I felt the strangest sensation. My skin split and cracked, my fingers became talons, my arm sprouted feathers. I stared down in horror and screeched but the Midnight Swan had slipped back into the lake and it was swimming away. It looked over its shoulder at me. All it said was, “Bring me the Egg. If you can.”

‘I opened my mouth to cry out but it was shaped all wrong and all I could say was kek kek. My body shrank. My bones hollowed. My limbs shrivelled. Cogs and wheels whirred in my chest. A key sprouted out and clicked in my side. I spread my arms and they were wings. And I flew, above the lake, over the garden wall, away. All the way home.’

He looked up. ‘And that is how I came to be in this unfortunate situation.’

There was silence. Birdsong seemed to come back from a long distance. Seren said carefully, ‘Thank you for telling us. It must have been … difficult.’

‘I’m not proud of the episode,’ the Crow muttered.

‘The Egg of the Midnight Swan,’ Tomos said. ‘That’s going to be tricky. If They have it…’

‘Exactly.’

‘So, did you try to find it?’

‘Well, er … it’s difficult. With Them. I tried to find the garden again but I have never been able to. Wherever it is, it’s not in this world. So Enoch and I just went looking for cures.’ It sank into a sudden morose heap of feathers. ‘There aren’t any of those; I know that now. I’m going to be like this for ever and ever. I just know it.’

Seren jumped up. ‘No, you don’t.’ She went out of the summerhouse and sat on the steps, and the sun was hot on her face. ‘Don’t worry. We have that Box now. The Box of the Midnight Swan. It’s got to help us.’

‘A Box no one can open!’ The Crow snorted. ‘And if my superb intelligence can’t work that problem out, how can a silly girl and a nosy boy help?’

‘Hey,’ Tomos objected. ‘I’m not nosy.’

‘You are.’

‘I’m just interested.’

Seren hugged her knees. ‘Don’t worry about getting the Box open,’ she said darkly. ‘I’m on the case now and you know my methods, Watson. It will be … elementary.’