Autumn pushed the pasta from one side of her plate to the other, picking at the meat like a bird.

‘Is there something wrong with your food?’ Magoo asked as he shovelled another mouthful in. ‘I’d have said it’s one of my better efforts.’

‘No, it’s delicious, sir,’ Autumn said. ‘I’m just not very hungry. I’ve been thinking about Mrs Vanden Boom and those letters – and everything else.’

‘I’ll get onto it as soon as we’ve eaten,’ Magoo said. The pages were sitting on the kitchen bench.

Max felt as if there were something stuck in his throat and was finding it hard to swallow. He was worried about his sister and Curtis – there was still something that didn’t sit right with him about the whole situation, even though he could have sworn it was her he’d talked to.

The boy had just twirled a long strand of spaghetti around his fork and raised it to his lips when the doorbell rang.

The three of them looked at each other.

‘Honestly, don’t people know not to visit at dinner time?’ Magoo said.

‘I’ll check the camera,’ Max said. He jumped up from his seat and ran to the screen on the wall.

‘It’s Mr Reffell,’ the boy said. ‘Mr Frizzle is with him.’

‘What on earth could they want?’ Magoo said.

‘They don’t know you’re here, sir, so maybe it’s better if we keep it that way,’ Max said.

The headmaster harrumphed, but gave a nod.

Max bounded up the stairs with Autumn on his heels.

‘Be careful, Max, what if it’s a trap?’ the girl said.

He’d already thought of that. The last thing he’d done when he was down in the lab was grab some weapons, which he now had in his pockets. There was a tiny taser, as well as a pen that fired poison darts – they weren’t strong enough to kill, but were perfect for disarming an assailant for a short period.

Max checked the screen by the front door before asking Monty Reffell and Elliot Frizzle what they wanted.

‘Please, Max, we need to talk to you,’ the history teacher said. ‘It’s very important.’

Max was pretty sure that Reff was on their side, but he had no idea about Frizzle. He paused for a moment before opening the door. The pair hurried inside, where they seemed surprised to find Autumn too.

Max stepped out onto the stoop and studied the street to see if the men could have been followed or if anyone was watching the house before closing the door and locking it.

‘Are your parents home? We’ve been trying to call Cordelia and your father but neither of them has picked up,’ Monty said.

‘No, Granny and Dad are away on business and Mum’s sick with the flu,’ Max said.

Elliot Frizzle looked as if he was about to have a heart attack. His face was pale and he couldn’t stand still. ‘We think something terrible’s happened to Mrs Vanden Boom.’

Max bit his lip.

‘She’s missing. Her whole house has been packed up and she’s gone. She’s not sick. The note Magoo sent the staff was a lie,’ Monty said. ‘Why would she just up and leave? She loves her job at school and in the Inventions Team.’

Max didn’t know what to say.

‘And,’ Elliot’s voice dropped to a whisper, ‘someone left this for me in my pigeon hole at school.’ He unfurled his hand to reveal a scarab beetle – the same as the one Derek had given the twins earlier.

Max and Autumn looked at one another.

Monty took a deep breath as if steeling himself for what was about to come next. ‘When you came to ask me about the meaning of scarab beetles before our history lesson, did you already know that someone was passing them out?’ the man asked.

Max shook his head. ‘We didn’t know about Mr Frizzle’s, but we had come by another one.’ Max pulled the trinket out of his pocket and passed it to the history teacher. ‘We’re not sure who it was intended for.’

‘What do you mean? Where did you find it?’ Monty asked.

Max really wanted to tell the man the truth – he couldn’t share everything but maybe he could reveal some of it.

‘A friend found it in his shop and gave it to us,’ Max said. That wasn’t a very satisfactory answer, and would probably just prompt a raft of further questions, but it was as much as he was prepared to say.

The four of them were standing awkwardly in the sitting room. Max would have asked them to sit down, but he was still considering the implications of the pair finding out that Mr MacGregor was downstairs – and he had already considered the idea that Magoo may have wandered into the pantry and discovered the screens. He didn’t want Magoo to know about the scarabs. Not when he and Tippie were still prime suspects.

‘You realise what this means,’ Monty said. ‘Someone is staging a coup. Your entire family is in terrible danger.’ He handed the scarab back to Max.

‘You need to contact your father and grandmother right away,’ Elliot added.

Max scratched his head. ‘Of course.’

‘Where’s your sister?’ Monty asked.

‘Upstairs looking after Mum,’ the boy lied.

‘Can we talk to Anna?’ Elliot said. ‘I don’t think you understand just how dire the situation is.’

‘Elliot and I are on your side, Max – we would never betray your grandmother,’ Monty assured him. Elliot nodded.

Max was about to say something when his phone rang. He looked at the screen. He had to take the call.

‘Excuse me a moment,’ the boy said. He listened intently, his eyes wide.

The boy gasped. ‘You need to get out of there. Go!’

Max heard a scuffle and shouting before the phone went dead.

He turned to Autumn and the others. The look of terror on his face was clear.

‘That was Doctor Foster. Someone got into the clinic and attacked Mrs Thornthwaite – and I think something’s happened to the doctor too.’

The gravity of the situation was far worse than anyone imagined.

‘What was Ida doing there?’ Monty asked.

Max ignored the question. ‘Are you both armed?’ He looked at the men.

Monty nodded. Elliot shook his head.

‘We’ll go to the vault on the way to the clinic,’ Max said.

They hurried downstairs to the kitchen, where Magoo was in the middle of washing up.

‘Mr MacGregor, we need to go to the clinic. Something’s happened. Doctor Foster is in trouble.’

Monty and Elliot looked at their boss, wondering what he was doing there.

‘Good heavens.’ Magoo threw the tea towel hanging over his shoulder onto the bench.

‘Follow me,’ Max said. ‘We’ll tell you everything on the way.’

Max looked at Autumn. There was no better test of Magoo’s loyalty than right now.