‘But, Felix, you almost went to chess club today. And that’s serious. We can’t let that happen again.’

‘I won’t.’

Jake looks at Granddad’s house, like he’s thinking of another plan. He’d be thinking even harder if he knew I was seeing chessboards in shop windows and on the back of buses.

‘What if he’s a spy?’ Jake suddenly blurts out.

‘What?’ I say disbelievingly.

Jake kneels up. ‘Your granddad. What if he’s a spy?’

‘But he’s not!’

‘But he might be. It’s weird that his curtains are always closed. Maybe it’s not to stop people looking in, but so he can hide behind them and spy on us.’

‘You’re being stupid,’ I say. ‘He’s just my granddad.’

‘But that’s the point,’ says Jake. ‘He’s just a granddad. No one would suspect a granddad. It’s a trick – that’s how they don’t get caught. They are careful and meticulous like your granddad, and they never leave evidence. I saw it on a film once – they shred every piece of paper after they’ve read it.’

‘Well, my granddad does tear paper into tiny pieces,’ I joke.

‘There! See! Your granddad could be the head of a Russian spy network!’

‘Jake,’ I laugh. ‘For a start he’s German, plus I don’t think the head of Russian spies would live in Bristol. And who’d want to know what happens at the diabetes clinic or at Lidl?’

‘But that would be a brilliant alibi; no one would even think it.’ Jake crawls to the edge of the platform. ‘We should follow him,’ he says. ‘Track his every manoeuvre.’

‘Jake.’ I roll my eyes. ‘Not now!’

‘I’m not doing it now. I’m going home for tea. We’ll spy on him after.’

‘I think it’s stupid,’ I say. ‘Anyway I can’t, because I’m playing chess with Granddad again.’

‘Of course!’ Jake huffs. ‘How could I ever forget . . . We’ll do it tomorrow then . . . Be here early, and bring your binoculars, because there’s only one way to catch a spy.’ Jake slides down the rope.

‘And what’s that?’

‘It’s obvious,’ he says, looking up at me. ‘Tomorrow we’ve got to do some spying of our own.’

Pass the Sauce

‘So what were you and your friend talking about in your tree?’ asks Granddad when I get back to his house.

‘What, Granddad?’

‘You and your friend. I saw you talking earlier.’

‘Oh, nothing,’ I say, cutting a piece of meat. ‘We were just talking about school,’ I add, thinking quickly. ‘We’re doing a project together in science.’ I feel bad for telling Jake about Granddad’s past, and from the way Granddad skipped the subject earlier I think he may have had enough of talking about it for one day. ‘What are we doing tonight?’ I ask brightly, trying to change the topic.