Sam and I are on an early morning spy-training mission with Mum since I’ll be doing the Training That Should Not Be Named after school. Mum texted Sam at six a.m. and then came into my room and ripped off my duvet – Sam definitely got the better wake-up call. It reminds me of Dan McGuire and the Midnight Feast Burglar – when Dan has to stay awake to catch a criminal who’s stealing famous chefs’ recipes in the middle of the night. I bet he was almost as tired as I am. It doesn’t help that apparently Mum’s decided to train us in the art of goobledy-gook.

‘First of all,’ Mum says. ‘I want you to learn a couple of cyphers so that you can code and de-code messages.’ She pulls out a piece of paper with a double row of letters on it and shows it to us. The letters of the alphabet run along the first row, and then in reverse underneath. ‘It’s called the reverse alphabet cipher,’ Mum says. ‘If you want to write an “a” you write “z” and so on.’

‘I see,’ says Sam. ‘And couldn’t you make it harder by shifting the alphabet underneath further along? So “a” equals a letter in the middle of the alphabet instead of the last letter?’

‘Exactly,’ my Mum says, beaming at Sam.

I get it, but it makes my head hurt when people start talking about one letter meaning another. I like it when ‘a’ means ‘a’ and ‘b’ means ‘b’ or even ‘b’ means ‘breakfast’ or ‘bread and butter’ – I’m hungry.

‘If there’s any reason for a contact not to give you a package, you may get a message written in code about what to do next,’ Mum goes on. She reaches into one of the gadget drawers and pulls out a slim black pen. ‘Or, it could be written using this. An infra-red pen.’

‘Is that like invisible ink?’ This is more like it!

Mum takes a sheet of paper from another drawer and quickly scribbles something on it with the pen. She holds up the paper – it’s still blank.

‘Blinding!’ I’ve always wanted to have some proper invisible ink. Before we went on the run, I did a lesson back at Bridleway Primary about using lemon or vinegar to write with but it didn’t work out too well. First, because you could still see a trace of the message, and second, because Mr Burnside stopped the lesson when my old friend Eddie used vinegar to write ‘Mr Burpslide’.

‘So how do you find out what it says?’ Sam leans in to get a closer look.

Mum pulls out what looks like a smartphone. ‘An infra-red reader,’ she tells us. ‘You pass this over the sheet and …’ She demonstrates and suddenly we can see what she’s written – ‘Bangers and Mash’.

‘Why don’t spies use that all the time instead of the code thing?’ I don’t see how reverse alphabet ciphers can compete with infra-red pens and readers.

‘Because technology can be faulty,’ Mum says. ‘If you lose the pen or the reader, you have no way of passing on or reading your message, but with the cypher, all you need is a piece of paper and a pen.’

Maybe, but for me, an infra-red pen still beats the alphabet every day of the week.

‘Just remember,’ Mum says. ‘If you want to communicate with each other about your mission, you must do it in code. For example, in one of my earliest missions it turned out that the postman was a plant – he wasn’t delivering information, he was trying to collect it. Moles can pop up anywhere – but you know that.’ Mum flashes me one of her laser looks.

Mum’s talking about when I thought that a swimming instructor was a thief instead of a spy when Sam and I were stopping the football memorabilia exhibition being stolen.

‘We’ll be careful, don’t worry,’ Sam says quickly.

‘Good,’ Mum replies.

I flash Sam a grateful look. Mum’s laser looks can make you feel pretty uncomfortable, especially this early in the morning.

‘Now, the other thing you might need is a distraction,’ Mum says. ‘We’ve had a few new gadgets in from HQ which I think you’ll find useful.’

She rummages around on the gadget shelves, muttering about Dad’s lack of organisation, and pulls out a couple of small cardboard boxes. ‘Here we go,’ she says. ‘The Scuttle Bug.’ She holds out what looks like a small black beetle. ‘Designed to make anyone following you, well, scuttle.’

‘It looks like a Hexbug.’ Sam peers closely at it, making a face. ‘Except this one looks real. It isn’t, is it?’

‘No, it’s not real, but it is clever. Watch.’ She sets the Scuttle Bug on the floor. The bug runs behind Mum’s chair leg. A second later we hear some shouting, as if it’s off in the distance. ‘Follow me! They’re over here!’ and the sound of feet running along a pavement, getting louder and louder. There’s a whistle and the noise increases – more feet, more shouting. Then the noise begins to lessen, as if the crowd is rounding another corner. The sound of running feet and shouts fades away into nothing.

Mum smiles. ‘They are all individually programmable but they also come in three pre-set levels – use Level 1 to give the impression of a couple of people approaching, use Level 2 if you want a medium-sized crowd – that’s what you just heard there – and Level 3 for a huge mob. It’s very good at scaring off anyone following you – as long as they’re worried about being noticed themselves. Which most enemy spies are.’

I decide that one of the first things Sam and I have to do is make a bunch of recordings – that is going to be serious fun. I reach out as she plucks another Scuttle Bug from the box and hands it over. ‘Nice.’

‘And then there’s this.’ Mum opens another box and pulls out a banana. ‘Your dad’s favourite.’

‘Is this your weird way of making sure I eat more fruit?’ I narrow my eyes at her.

Mum shakes her head. ‘This isn’t a piece of fruit you’d want to eat. It’s called a Banana Slip.’ She peels the skin down one side and throws it on the ground. Immediately a pool of liquid appears around it. ‘That’s chemically altered cooking oil, ten times slippier than almost any other liquid substance,’ she says. ‘You peel the activating skin, and as soon as the banana hits the ground the liquid is released and spreads up to three feet around it. If someone is chasing after you, even if they try to dodge the banana, they’ll still end up putting their foot in the oil and slipping up.’

I laugh. ‘Brilliant!’

Mum holds out a cloth. ‘Yeah, until you have to clean up the mess.’

‘Wait – why do I have to clean it up, you’re the one who threw it on the floor!’

Mum just looks at me and keeps holding the cloth until I take it. She’s basically pulling the Grown-Up Card.

I’m telling you, you’ve never seen mess until you’ve seen a Banana Slip slick.

Once I’ve managed to get the oil off the floor, Mum gives us a set of ciphers, a couple of infra-red pens and readers and packs us off to school.

Sometimes being a spy can be quite hard work.