I frowned. ‘Did you help us save Scotland?’

‘I got you information.’

‘Information that in the end had nothing to do with zombies.’

He shrugged. ‘That wasn’t my fault.’

True. ‘Well,’ I said, ‘this time it’s witches we are hoping to save.’ My light-hearted tone dropped several notches. ‘Seven are already dead and we expect there will be more if we don’t catch the bastard who’s doing it.’

Iqbal’s humour and banter vanished in an instant. ‘Go on.’

I disentangled Brutus’s claws from several of my curls while Winter explained. ‘Right now,’ he said, ‘we’re playing the waiting game.’ The frustration in his voice made it clear how annoying he found that. ‘We’re waiting on the police telling us where the coven members’ post is being re-directed to. We’re waiting on the Order working through their files to find out what happened with the coven’s application to become Order witches. And, unfortunately, we’re waiting on Blackbeard making another move.’

‘What?’ shrieked the ghost in my ear. ‘That’s your plan? To wait until he kills more witches? That’s ridiculous! That’s not a plan!’

I winced and stepped away. Even if I secretly agreed with him, technically there was more to it than waiting for further deaths.

Brutus hissed loudly and wriggled out of my arms so he could dart into the corner where it was apparently safer. ‘Why didn’t you tell me you could see ghosts?’ I asked him as he shot behind another dusty pile of books.

Brutus bobbed his head up from behind the literary parapet and flicked me a look as if to say I was being stupid and that I’d never have believed him. I sighed. Yeah, he was probably right; it wasn’t worth getting into now.

Iqbal coughed pointedly. ‘Well,’ he said, ‘there is definitely one thing I can help with. It came up in my research for my thesis. If you’re going to explore the history of magic in the British Isles then you also need to explore the absence of magic too.’

Both Winter and I leaned in. ‘Go on.’

‘Nulls,’ he said. ‘People who are entirely unaffected by magic. It doesn’t matter what you throw at them or how powerful a witch you are, they’re immune.’

‘Immune to magic?’ I said slowly. How on earth was that even possible? I looked at Winter; he seemed just as baffled as I was. ‘Have you ever heard of a null?’

‘No.’ He ran a hand through his hair. ‘But if that’s what our Blackbeard is, it makes a lot of sense.’

‘If it makes you feel any better,’ Iqbal said, ‘they’re incredibly rare. We’re talking about maybe one person in a million who’s affected, so it stands to reason that you don’t often hear about them.’

I grimaced. ‘Better odds than being a serial killer,’ I said. ‘Probably.’

‘Well,’ Iqbal demurred, ‘your guy is not a serial killer, he’s a mass murderer. Until he’s actually killed more than three people on separate occasions, he doesn’t count as a serial killer.’ He scratched his head. ‘So, uh, there’s that.’

Whoop-de-do.

‘This could be good news,’ Winter said. I glanced at him askance. I couldn’t possibly see how. ‘Someone somewhere must have noticed that Blackbeard is a null. It might have been a schoolteacher or a friend or a doctor. But whoever it was or whenever it happened, nulls are rare enough that there must be a record of who he really is. It might not lead us right to him but it could teach us a great deal about him.’

Okay, that kind of made sense. ‘So, as the Arcane Branch expert among us,’ I said, ‘how would you search the records for him?’

‘I’d put in a bi-request for Order and police records. For something as vital as this, it would be a rush job so it would take two or three days. Obviously, I can’t request it in my current position.’

I was getting a headache. ‘We need to go back to the Ipsissimus and get him to do it.’ Winter nodded. He really didn’t look happy about it. ‘Maybe you should re-join…’ I began. His expression stopped me from finishing my sentence.

‘Is there anything else about nulls that you can tell us?’ he asked Iqbal. ‘Anything at all?’

My friend shrugged. ‘There’s not much to tell. They’re just the same as any ordinary person. They don’t have magic and magic can’t affect them. To stop a null you need to use other means.’ He paused. ‘You two are smart. You can work it out.’

Judging by the expression on Winter’s face, he felt as doubtful as I did. Magic was what we did; it was in our blood and in our DNA. If we couldn’t rely on it, I didn’t know what we could do. It felt like our chances of catching Blackbeard and bringing him to justice had gone from slim to none.

The ghost frowned at me. ‘Give me a break,’ he complained. ‘You think that just because you’ve found someone who you can’t bespell it’s the end of the world.’

I glared at him. ‘It was the end of Clare Rees’s world.’ And Karen’s. And Paul’s. And Amy’s. Not to mention the other three whom I had yet to meet but who I knew were out there somewhere.

‘Death isn’t so bad,’ the ghost went on. ‘It’s the hanging around that sucks. All this waiting for something to happen and nothing ever does. Being here is like being stuck at the dentist and waiting to have your teeth pulled without anaesthetic. Except you don’t know when it’s going to happen. Or if it’s ever going to happen. You just know that you can’t do anything apart from wait.’

Damn. ‘I’m … sorry,’ I said. It was inane but true.

Crazy Hair sighed. ‘It’s not your fault.’

‘Who is it, Ivy?’ Iqbal asked. ‘Who’s the ghost? Why are they here haunting me?’

I raised my eyebrows in question. Crazy Hair shrugged. ‘I’m not haunting him. I used to work here. It’s a good place. I normally hang around the canteen because that’s where you get all the best gossip but I got word that Grenville wanted me here. He really does want to talk to you.’

It was my turn to shrug. ‘I’ll try to drop in when we go to see the Ipsissimus.’ The current Ipsissimus. Man, this could get confusing. ‘How can I help you?’ I asked. ‘How can I help you move on? Who do I need to talk to?’

A calculating look flitted across his expression. ‘You’d do that?’

I blinked. ‘Of course.’

‘It’s not a person who can free me,’ he said. ‘It’s a plaque.’

‘I thought you guys wanted things like plaques.’ And shrines and paintings and whatever.

‘You guys?’ he snorted. ‘You’ll be dead one day too, you know. Then you’ll see.’

Iqbal reached forward and touched my elbow. ‘I can only hear a bit of what’s going on,’ he said, ‘but if it’s a plaque you’re looking for, I might know what you mean.’ An expression of reverence crossed his face. ‘Is the ghost you’re talking to male, with frizzy hair that looks like yours? You know, like it’s been electrocuted?’

‘Electrocuted?’ the spirit spat. ‘Just because I had better things to do than worry about my appearance! I’ll have you know that I was the one who discovered the gene that is responsible for determining magic ability. Hundreds, no, thousands of witches have been discovered because of my work, instead of being left to languish in anonymity!’

I felt a sudden kinship with the phantom. After all, I also had better things to do than worry about my appearance. My better things weren’t amazing scientific breakthroughs, however; they were amazing days snuggled up underneath my duvet. I decided I probably shouldn’t say that.

‘That’s him,’ I said to Iqbal instead.

He fixed his gaze on a point over the ghost’s shoulder. ‘Professor Wiggins,’ he breathed. ‘It’s a genuine pleasure.’

Crazy Hair – or rather Professor Wiggins – looked slightly embarrassed. ‘That’s okay,’ he said gruffly. He glanced at me. ‘You should tell your friend that he needs to have another look at the third chapter. He’s got his sums wrong.’