I’ve got to hand it to Boydy. Lying under pressure: it’s quite a skill to be so good at it by the age of thirteen. Mind you, the story he comes up with is so utterly far-fetched that I just stand there, invisibly open-mouthed at his fluent deception.

‘Ah, you’re up! Oh good – I didn’t want to wake you. Ethel’s fine, she’s just, erm … a bit poorly and has gone to bed in our spare room.’

I’m standing right next to him as he says this, of course, and my gaze darts from one to the other.

‘You’d better come in,’ says Gram.

She’s not buying this, I can tell. Not yet.

I follow Boydy through the back door into the kitchen, and stand in the corner, watching everything. This time, Lady doesn’t freak out, although I see her nose go up as she smells my presence. Instead she just slinks away to the front room.

In the light, the extent of Boydy’s injuries is more apparent. The back of his jeans is torn and soaked with blood.

‘Get those off,’ commands Gram. ‘We’ll clean you up and you can tell me exactly what is going on.’

So far, I have got to the age of nearly thirteen without once having to see a teenage boy’s bare bottom. Now I get to see two in the space of one evening.

Oh, lucky me.

‘How did this happen?’ asks Gram quite kindly.

It does look bad. There are puncture marks on the top of his thigh, and there’s a tear in the flesh of his large, pale buttock. Boydy leans over the kitchen table as Gram gets some witch hazel and cotton wool. He directs his comments over his shoulder.

‘I was attacked by a dog in the back lane.’

‘Good heavens. We should call the police! An attack like this is very serious.’

‘Er, no … don’t do that!’ He sounds desperate.

‘Why ever not, Elliot?’

‘I was, erm …’

Honestly, I can almost hear the cogs turning in his head as he thinks on his feet.

‘I was … taking a shortcut through someone’s back garden and it was a guard dog!’ He ends up sounding very pleased with this fib, and continues, ‘You see, I was coming round to tell you about Effow, because – ooh, that stings! – because Mum told me to take responsibility.’

Good. Clever. Invoke the command of a responsible adult.

‘Responsibility for what, Elliot?’

‘I think she – in fact, I know she – erm … drank some alcohol. Ooooow!’

Oh, thanks a lot, Boydy. Thanks a huge, great, gift-wrapped bundle.

‘Alcohol? Oh, Elliot, oh no, no, no.’

I now know that, of all the things you could say to Gram, this is probably the worst, given what she went through with my mum. The colour has drained from her face, and she stands holding the bottle of witch hazel, shaking her head.

‘I’m sorry, Mrs Leatherhead. It was only one beer. She didn’t even like it, and then she threw up and my mum put her to bed.’

‘Where did she get it? Did you give it to her?’ Gram renews her nursing with extra vigour.

‘I don’t know, Mrs L. Oooow! Honestly, it was just her. We only had Sprite and Fanta. I’m really sorry. I should have stopped her. Aaiiieee!’

Good, I’m thinking. I’m glad it’s hurting. It’s bad enough that he lied about me drinking alcohol. For a start, it’s disgusting. (I’ve never had any, but I have smelt wine before and I don’t think I will ever drink it. Why would you drink fruit juice that’s gone off, which is all it is as far as I can tell?) And for another thing, why choose that? He could have just said I’d overindulged on the pizza. You know, one slice of pepperoni and mushroom too many and up it all came, then I got packed off to bed.

Too much imagination, that’s Boydy’s problem.

Gram’s got the sticking plaster out now and is applying it to Boydy’s bitten bum.

‘Well, frankly, Elliot, I am surprised and disappointed. I thought you were more responsible than this. Although I appreciate you coming round to tell me in person. Right, you’re all patched up. It’s too late now, but I shall be calling your mother in the morning. And tell Ethel to come here before she goes to school.’

Boydy – to my great relief – has pulled his trousers back up and is hobbling to the back door.

Gram has her back to us both as she puts the medicine away.

Boydy takes out Jesmond’s mobile phone from his jeans pocket and holds it up to me. He points at it, then to himself, and then makes a wiping motion with his hand.

He’s going to wipe Jesmond’s phone. Good. You can do that without a passcode. In fact, that’s pretty much all you can do without a passcode: restore it to a blank phone, erasing all saved data.

He then takes out my phone that I’d given him before and puts it out of Gram’s eyeline, behind the toaster.

‘Thank you, Mrs Leatherhead. And, erm … sorry.’

‘Goodbye, Elliot. Pull the back door shut behind you.’

And if I thought I had had enough heart-stopping tension and excitement for one day, what comes next makes everything so far seem like a quiet evening watching Robson Green’s Country Walks.

I’m still in the kitchen, remember, trying not to put weight on my sore heel.

I have decided. Now is the time to bring Gram on board with the invisible stuff.

I can prove it, because I’m invisible.

I’m just thinking about what words to use: ‘Hey, Gram, remember what I said about being invisible?’ But I’m still kind of … what? Shy? No. Not shy, but …

Anyway, it doesn’t matter because Gram starts talking to someone who – apparently – has been in the sitting room all along.

‘It’s OK. He’s gone. You can come through.’