The rat – Mrs Cuffy – skittered about on the chair, and I jumped up and down on the spot laughing my head off. This was more like it! Who needed science out of books – or science teachers!

But about three seconds later, I heard footsteps coming up the hall. Then it hit me. What on earth had I done? And, more importantly, what was I going to do now?

The footsteps were coming closer. It had to be Mary, already on her way back from Mrs Winkle’s office.

Now, even though she was my best friend, Mary didn’t know I was a witch. I always kept school and witchcraft separate and never told anyone in case they all treated me like a total weirdo.

If I let her in, she was bound to ask where Mrs Cuffy was – and then she would see the rat and faint or something …

‘Rats! – I mean, blast!’ I whispered, gazing at Mrs Cuffy. She made a furious chattering sound, crossed her little ratty arms, and tapped one foot. Her black eyes glittered at me.

Quick as I could, I jumped back inside my magic star, pointed at her again and chanted:

Nothing happened – except Mrs Cuffy squeaked and chattered even louder. I’d have to think of something else. I rushed to the door and tried to block Mary.

‘Mary!’ I said, draping my arm across the doorway. ‘So nice to see you again!’

‘Mrs Winkle said I had to do as I was told,’ she said glumly. She looked at me with red-rimmed eyes. ‘I suppose we’d better get on with it, or we’ll be in even more trouble.’

‘Good news!’ I said. ‘Mrs Cuffy changed her mind – we’re off the hook!’

‘What?’ she said. ‘What do you mean, off the hook?’

‘No detention,’ I said. ‘Mrs Cuffy’s busy.’

‘Are you sure?’ said Mary, looking confused. ‘It’s not like her to miss a chance to inflict a punishment.’

‘Yep,’ I said. ‘After you left, she droned on at me for a while – but then she said we had to go home! Straight away. Right now. Without delay.’

I could hardly believe how many lies were tripping so easily out of my mouth. Mary tried to peep over my shoulder.

‘Is she still in there?’ she whispered.

‘Not exactly,’ I said. ‘She had an urgent appointment at the … the vet, and she left in a hurry. Come on, she said we mustn’t hang about!’

‘Great!’ said Mary, her face breaking into a broad, dimpled grin. ‘I’ll just get my bag.’

‘Get it tomorrow!’ I said. I tried to take Mary’s arm and hurry her down the corridor.

‘Don’t be daft,’ said Mary, shoving me out of the way. ‘It’s my gym stuff and it’s just inside the door …’

Mary stepped through the door. I closed my eyes, put my fingers in my ears and waited. I didn’t have to wait long.

‘WAAAAAAHH!! WAAAAAAHH!!!’ screamed Mary, rushing out of the classroom and nearly knocking me over. ‘RATS! Rats! In there! Look!’

‘One rat,’ I said, peering around the door. ‘Don’t exaggerate.’

‘You knew there was a rat in there?’ said Mary.

‘Sure,’ I said, shrugging. ‘It just sort of appeared while you were out. Come on, let’s go.’

‘Anna, are you NUTS?’ said Mary. ‘Those things carry diseases and everything! We need to do something!’ she said. ‘I think I’d better take another look.’

I sighed.

‘If you insist,’ I said. We edged back into the classroom.

On the chair, Mrs Cuffy crouched and glared. She balled one front paw into a fist and shook it at me.

Mary gasped.

‘Is that thing threatening you?’ she said. ‘Are rats even supposed to be able to do that?!’

No sooner were the words out of her mouth than Mrs Cuffy bared her pointed yellow teeth and reared up on her back legs, screeching and spitting in pure temper. Like a flash, she shot between Mary and me, scampered through the open door and disappeared down the corridor.

I took a deep breath.

‘Friendly animal,’ I said. ‘Can we go now?’

‘But, Anna! It’s a dirty old rat!’ said Mary. ‘We need to at least tell Mrs Winkle? Or the caretaker?’

‘No need for that,’ I said. I picked up her bag and dragged her down the corridor. ‘Do you want to be here all night and miss gym?’

That did the trick. Mary Maxwell loved her gym.

‘I suppose you’re right,’ she said. ‘Ugh! Rats live in drains and rubbish tips, you know! I saw a programme about it on TV …’