Charlie Bone and the Blue Boa. Jenny Nimmo

Fidelio didn’t. ‘Hi, Olivia! Are you playing a racoon this term?’ he asked as he strolled up.

      ‘Who knows,’ said Olivia. ‘Manfred’s writing the end-of-term play – with Zelda’s help, of course.’ She nodded at a group of sixth formers on the other side of the playing field. Manfred, the head boy, was talking earnestly to Zelda Dobinski, a tall, skinny girl with a large nose.

      Charlie noticed that Manfred’s sidekick, Asa Pike, was staring at Belle walking arm in arm with Dorcas Loom. Asa broke away from the group of sixth formers and walked across to the two girls. He had a crooked smile on his pale, weaselly face and, as he approached the girls, he ran his fingers through his red hair, almost as if he were trying to tidy himself up.

      Charlie grabbed Fidelio’s arm. ‘Look!’ he said. ‘Asa’s speaking to a junior. I bet that’s never happened before.’

      ‘Except when he’s been telling them off,’ said Fidelio.

      ‘That girl with Dorcas is really pretty,’ muttered Olivia.

      ‘Her name’s Belle,’ Charlie told her. ‘She’s living with my great-aunts.’

      Olivia whistled. ‘I can’t imagine any child living with them. By the way, have you seen Emma?’

      The boys shook their heads and Olivia sauntered off to look for her friend. She eventually found Emma sitting on a log by the old castle walls. She was holding what appeared to be a small, neatly-written letter.

      ‘What’s up, Em?’ said Olivia, perching beside her.

      ‘I found this by Mr Boldova’s desk.’ Emma held up the letter. ‘It must have fallen out of his pocket. I didn’t mean to read it. I meant to give it back, but then I saw something and . . . well, look.’

      Olivia took the letter and read,

       My dear Samuel,

       We have it on good authority that the shifter is heading your way. What form it will take God only knows. But it will recognise you, so get out of that place, Samuel, as soon as you can. I have resigned myself to losing Ollie, although your mother still grieves. She can’t stop herself from buying the jam he so loved. We have a room full of the stuff now, and it breaks my heart to see it. I know you feel your brother’s loss as deeply as we do, but you must give up the search. We could not bear to lose you, too. Come home soon.

       Dad

      ‘What d’you think?’ said Emma.

      ‘Interesting,’ said Olivia. ‘But I think you should put the letter back on Mr B’s desk. It’s none of our business who he is, or what he’s up to.’

      ‘But it is.’ Emma pushed her long blonde hair out of her face. She was very agitated. Olivia knew her friend liked Mr Boldova. He was young for a teacher, but he was good at art, and he seemed to be on the children’s side whenever there was trouble.

      ‘You remember when Manfred locked me in the attic, well someone let me out, and whoever it was had a passion for jam. I heard Manfred teasing him about it. I know this sounds peculiar but he, or she, seemed to be invisible. And then there was this boy, Ollie Sparks, who was lost in the attics ages ago. He got out eventually and everyone thought he’d gone home, but maybe he didn’t. Maybe he was punished. Maybe he’s still up there.’ She glanced up at the tiled roof of the academy.

      ‘Hmm. So what d’you want to do about it?’ asked Olivia.

      Emma shook her head. ‘I don’t know.’

      A hunting horn sounded across the garden and the two friends agreed to talk again in the afternoon break.

      Emma’s next lesson was French, but first she ran to the art room. It was empty and she was just sneaking the letter on to Mr Boldova’s desk, when he walked in.

      ‘Emma?’ He looked surprised. ‘Shouldn’t you be in another lesson?’

      ‘French, sir. But, it’s just that I . . .well, I’m really sorry, but I read your letter and . . .’ Suddenly Emma found herself telling Mr Boldova about the invisible presence in the attic, the person who liked jam.

      Mr Boldova listened intently and then he sat at his desk and said, ‘Thank you, Emma. Thank you very much. Will you promise not to tell anyone else about this?’

      ‘But I’ve already told Olivia Vertigo, and she might tell some of our friends.’

      ‘Can you trust them, Emma?’

      ‘With my life,’ said Emma.

      Mr Boldova smiled. He looked a rather outdoor sort of person for an artist. His face was tanned and his dark brown hair was drawn back in a ponytail, somewhat like Manfred Bloor’s, only Manfred’s hair was black and stringy.

      Emma said, ‘What happened to Ollie, sir? We thought he’d gone home after he escaped from the attics.’

      ‘I’m afraid not,’ sighed the teacher. ‘Our parents live a long way from here. Dr Bloor agreed to put Ollie on a train in the company of the matron’s sister, a Miss Yewbeam. She told us that Ollie went to get an orange juice from the station cafeteria, and never came back.’

      ‘I bet he never even got as far as the train,’ said Emma hotly. ‘Those Yewbeams are evil. They’re Charlie Bone’s great-aunts, you know, and they make his life a misery.’

      ‘Ah, Charlie Bone,’ Mr Boldova said thoughtfully.

      ‘I’d like to help Ollie,’ Emma went on. ‘He helped me, you see, and I could probably find the place where he’s kept.’

      ‘Better leave it to me, Emma. It could be dangerous.’

      ‘Sounds like it could be dangerous for you too, sir.’

      ‘I can take care of myself,’ Mr Boldova said cheerfully. ‘Now run along to your French lesson.’

      Emma went, but she didn’t hurry. She had too much on her mind. She was ten minutes late for her French lesson, and Madame Tessier was furious. She was an excitable woman and always hated the first day of term. She missed the sunny French city where she had been born, and complained constantly about the gloomy, grey academy, with its creaking floorboards, erratic heating and poor lighting. She was only there because Dr Bloor offered her a salary she couldn’t resist.

      ‘Go! Go!’ she shrieked at Emma. ‘You don’t want my lesson, you don’t come in. It eez too late. So allez – allez!’ She waved her long fingers at Emma. ‘Get out!’

      Emma got out – quickly.

      ‘You too,’ came a husky whisper.

      Emma looked down the corridor and saw Charlie Bone standing outside the history room. He had just said that Napoleon was the Emperor of Russia. Mr Pope, the history teacher, had screamed at Charlie, telling him he was an ignoramus, and he didn’t want to see him in his class a minute longer.

      ‘I didn’t really hear the question.’ Charlie’s loud whisper echoed across to Emma. ‘I was thinking about a dog.’

      Emma glanced up and down the corridor. There was no one about. ‘What dog?’ she whispered.

      In as quiet a voice as he could manage, Charlie told Emma about Benjamin and Runner Bean. ‘Why were you sent out?’ he asked.

      ‘I was just late,’ said Emma. She recounted her conversation with Mr Boldova.

      Charlie’s eyes gleamed with interest. Yet another mention of someone dangerous on the move. Was it possible that they were one and the same?

      ‘So you reckon Ollie Sparks is in the attics?’ He paused and looked thoughtfully at the ceiling. ‘Let’s go and look, shall we?’

      Emma was horrified. ‘What, now?’

      ‘I can’t think of a better