From nowhere, Archie caught the scent of spice: ginger. Was Tablet cooking? As the windows were open, the smell could have come from anywhere. But he remembered how the same scent had led them to Belle’s portrait in the first place. He closed his eyes and inhaled. His mind began to clear, and he felt his senses sharpen. Opening his eyes again, he stood up in front of the picture, this time saying aloud: ‘Look where my gaze alights.’

Archie noticed something about the mirror Belle was looking at in the painting. She wasn’t looking at herself. She was using it to look behind her, over her shoulder! She was looking at the little statue of Corignis, the dragon who died to save the Wyrdie Tree. The green eye of the dragon flickered. Archie frowned.

‘Hang on,’ he said. ‘Honey dragons have golden eyes, not green!’ And it was blinking at him! No, not blinking – it was glinting! There was a green jewel embedded into the picture itself, sunk into the wooden panel on to which the portrait had been painted. This was what Belle was gazing at! ‘The Treeheart has been hidden in the painting all along, right under the noses of generations of McBudges.’

Archie lightly touched the jewel. The painted dragon suddenly moved its head and transformed. The whole picture was enchanted! Corignis was now a real dragon, clinging to the painting with very solid-looking claws.

As they watched in astonishment, the creature’s eyelids opened wide, like a flower opening its petals. The left eye was the usual golden colour of honey dragons, but the right was emerald green and sparkling. The little dragon blinked and the jewel dropped out of its eye and into Archie’s waiting hand.

‘I’ve found it!’ Archie laughed with relief. He could hardly believe it. ‘The Jewel of Renewal. Clever old Belle. What a great hiding place!’

‘I bet the wood that was used to make the painting came from the forest,’ said Billy, ‘from one of the magical trees.’

The dragon – which now had two golden eyes – settled back into the picture and didn’t move again. The Treeheart had been handed on, from one Guardian to another, and it was Archie’s responsibility now.

Fliss and Billy gasped as the jewel sparkled in Archie’s hand, spots of bright, green light reflecting on to the surrounding walls.

Fliss’s bag began to rattle and jump about violently.

‘Whoa!’ said Billy. ‘Have you something else alive in there?’

‘No,’ said Fliss, dropping the bag to the floor. ‘Only Cogswallop.’

At that moment, the little clockwork creature waddled out of the bag, and began running in agitated circles at their feet. Then its wooden wings began to flap and the dragon took off, whirring in a spiral as it flew.

‘I’ve never seen Cogswallop do that before,’ said Fliss, with a laugh. But the hairs on Archie’s neck stood up. There was bad magic at work here. Before he could act, Cogswallop swooped down, his jaws plucking the Treeheart from Archie’s fingers. They watched, horrified, as the toy flew bumpily out of the room.

‘Jewel thief!’ yelled Billy. They raced downstairs after the clockwork dragon, Sherbet running in front and barking angrily.

‘I don’t understand it!’ said Fliss, stuffing Blossom unceremoniously back into her bag as they ran out of the open front door of the Hall. ‘What does Cogswallop want with the Treeheart?’

‘It’s not Cogswallop,’ said Archie. ‘Preen must be controlling him.’

‘But –’ began Fliss. She was remembering something, but there was no time to talk. The thief swept down the drive, into the street and towards the factory gates, high over the heads and placards of the N.I.C.E. protestors, who were still outside and had grown in number, despite the heat. Luckily, Mr Preen was nowhere to be seen. The children tried to make their way quietly through the crowd, hoping to go unnoticed.

‘That’s Archie McBudge!’ said a voice that made Archie’s heart sink. It was Miss McTwang, who was carrying a banner that said NO SUGAR – I’M SWEET ENOUGH, THANK YOU!.

‘Please, let us through!’ begged Archie. ‘It’s really important!’ The protestors weren’t prepared to listen. A large group had surrounded them, chanting. He recognised some of their faces.

‘CHUCK OUT CHOCOLATE!’ It was Mrs Crumple who ran the hillwalking club. She always had an emergency chocolate bar on her, in case she got stuck up a mountain!

‘STAMP OUT SWEETS!’ That was Old MacTwistie, whose usual hobby was sitting on street corners waving his walking stick at cyclists for no apparent reason.

‘N.I.C.E. NOT NAUGHTY!’ And that was Angus Beanfrost. He hadn’t been near a dentist in years!

‘MY BANNER IS ON FIRE!’ shouted Peony Prestwick, which was a bit of an odd slogan. ‘No, it really is – look!’

Whilst attention was on Archie, Fliss had opened her bag, allowing Blossom to poke her head out for a moment and send a burst of flame upwards. One sign had caught alight, and others quickly followed. There were screams and shouts from some of the protesters as they tried to keep the burning card away from themselves, and people ran in every direction, throwing the placards to the ground and stamping on the fire to put it out.

Archie and the others took advantage of the confusion and hurried into the street. Through the smoky haze, they just caught sight of the clockwork dragon as it turned a corner.

‘Where’s he going?’ said Billy, as they trailed after it. ‘If we’re not careful, we’ll lose him in all this smoke.’

‘It’s not smoke,’ said Archie, fear rising in his voice, as tendrils of fog crept around their feet. ‘It’s that Mirk mist – like we ran into in the old forest! And the dragon is heading for the graveyard …’