He was known as the Horseman. If anyone asked, he was from Monopolis. Certainly he had met Dog there, when they had both been in prison and escaped together. But then, working together to achieve anything was as far as you could get from being typically Monopolitan behaviour. If anyone commented on this to Dog, she shrugged it off. 'I may have been whelped there, but I don't think I was ever a true Monopolitan at heart. I need someone to fetch sticks for.'

As for Q, there was no mystery as to why he had joined the Horseman's rag-tag group of followers. The gadget-making ram was from Scrabble originally, and Scrabblers preferred to work in groups, preferably of seven people. They feared loneliness above everything – and an unmarried ram like Q had little prospect of achieving anything alone.

'But I thought ewes outnumbered rams four to one on your world?' the Horseman asked once, when Q was in a cheerful and talkative mood after chewing his favourite narcotic leaf.

'Of course they do. If I'd got out early, I could've had them queueing up to follow me. But I was too busy improving myself, when I was young. I wasn't satisfied with what I had – kept throwing my hands back.'

'Throwing them back? What does that mean?' Dog asked.

'Well, I started off with normal hooves,' Q pointed out, holding out his forelegs to display his long, deft-fingered hands. 'I knew those weren't going to be any good to me as a mechanic, so I cast the Exchange Hand spell to get something useful instead.' He realised that both Dog and the Horseman were looking blank. 'Don't you have that spell on your worlds – uh, world?' he asked.

'You mean you can exchange limbs like property?' asked Dog. 'If you met a human who had hands they didn't mind swapping for hooves, and maybe you might throw in some cash to sweeten the deal…'

'No, nothing so organised,' said Q. 'It's completely random. The spell severs your original hand and you get something back in exchange – the first time I tried it, I ended up with a mouse's right paw and a dolphin's left flipper. And of course, it takes time for the bone and nerves and muscles on the grafted hand to grow into yours so that you can actually use it, so you need to take time off to recover. By the time I was ready to do anything with my life, all the ewes had already made plans for their future that didn't involve me. That was when I started chewing qat – and yes, I knew it was stupid, I knew it disrupted the flow of my qi, but it was the only thing that helped me stop worrying about being left on the shelf. And then, just when my life was at its worst, a Red Knight came riding by to rescue me.'

The Horseman started. He realised that both the ram and the terrier were grinning at him. 'You knew?' he said.

'What, that you were a Chessan spy?' said Q casually. 'Of course – we've known for years.'

'But I had a bet on with Q that you weren't entirely Chessan,' added Dog. 'You're a bit too familiar with secret shortcuts and mysterious murders for that, so I'd guess – part Cluedonian ancestry? And brought up there for part of your youth?'

'The Cluedonians never did work out how Miss Scarlet disappeared into the passage from the Lounge and never emerged in the Conservatory, did they?' said Q. 'That would have been – a year or two before you were born, I'd guess. But then, about ten years ago, the most successful detective on Cluedo was a mysterious figure called Ensign Rose, and nobody seemed to know where he came from.'

The Horseman – or rather, the Red Knight – laughed. 'I was tempted to call myself Captain Scarlet, but I was afraid it would be a bit too obvious. If my mother went back now, she might be able to provide enough evidence to clear herself of murdering Dr Black, but not the desertion and treason charges – and with all the work she's got to deal with in our world, she has to keep running just to stay in the same place.'

'Is that "work" as in imposing Chessan imperialist ideals on the Draughtsmen?' enquired Dog.

'It's not like that!' protested the Red Knight. 'I mean, yes, after my mother, a rook and a pawn defeated the last White King, they did suggest to my father that we needed to find something else for Chessmen and Chesswomen to do instead of fighting each other, and he did decide that the obvious way to bring about co-operation was to invade Draughts.

'But – well, that wasn't the only reason. Draughtsmen may be terribly egalitarian, in that everyone starts off as a pawn, promotion is strictly by merit, and any number of people can become kings. But in practice that means that on the battlefield, instead of each side having one sovereign leader whom the other side is trying to capture, they just fight to annihilate each other. Their racial hatred was just as deeply entrenched as ours was – black Draughtsmen against white, or white Chessmen against red. But when we invaded – first of all, the Draughtsmen stopped killing each other to focus on killing us, just as we'd stopped killing each other to focus on outmanoeuvring them. But then, when they realised our organisation was better and they couldn't win, my mother managed to talk them into surrendering. She pointed out that back on Cluedo, killing even one person was a crime, but on Draughts, for one half of the population to slaughter the other half was seen as a worthy goal.

'Anyway, all that was years ago. The Chessan Empire is fairly cosmopolitan these days – it's not at all unusual to see pink Chessmen or grey Draughtsmen. When the White Queen got married to a white Draughts king last year, plenty of people were saying it was a pity she hadn't chosen a black Draughtsman.'

'So – where do you want us to help you invade next? The Republic of Backgammon?' There was no criticism in Dog's voice. Monopolitans accepted hostile takeovers as a normal part of life. And everyone knew that the more conservative Draughtsmen were bitter about their countrymen who had seceded to set up a more liberal establishment on Backgammon.

'No. We're not looking to invade anywhere else at the moment. Do you believe me?'

Dog considered. 'I think we should,' she suggested. 'Chessmen don't keep secrets – not like Scrabblers!' she added with a wink at Q.

'Cluedonians do, though,' Q pointed out. 'And Chessmen may not lie exactly, but they're not above being manipulative, or distracting attention from their real goals – or sacrificing pawns,' he added darkly.

'And they don't have slaves on your world?' retorted Dog. 'At least the Chessmen consider that even pawns have some value. We've all heard about the blanks on Scrabble – slaves who can be made to do any kind of work without being paid for it! At least on Monopolis, everyone starts with nothing and everyone has an equal chance to end up owning everything, whether you're an old boot or a racing car.'

'It isn't quite like that,' Q pointed out. 'Scrabble work gangs are paid by the group's achievements, not individually, and blanks are the most prized members of society because they can learn to do any kind of work. I'd have been nearly as glad to marry a blank as a ewe – and if I'd happened to be born a blank, instead of a high-status specialist with limited career options, I'd have had more chance to join a team which was achieving something worthwhile.'

Dog considered this for a minute. 'I'd never thought of it like that before,' she admitted.

'No,' said the Red Knight. 'And that is why I'm a spy. We truly aren't planning to invade other worlds – though we certainly need to know more about tactics on neighbouring worlds like Shogi and Xiangqi that have a militaristic culture like ours, in case they try invading us. But mainly, I'm trying to learn about different ways of living together that could make the Chessan Empire a better place. For example, on the People's Republic of Backgammon, they never kill, even in battle – they just take prisoners.'

'Yeah, and they do that often enough where I come from, too,' growled Dog. 'If you can't bribe your way out, and don't have the luck to break out, you just have to sit tight until your sentence is up – and in the meantime, you can't do deals or even claim rent on your properties.'

'That's because Monopolitans are all out for themselves,' pointed out the Red Knight. 'On Backgammon, if someone is taken prisoner, their side will do everything they can to rescue them, before getting on with anything else.'

'Don't they have a no-kill policy on Shogi, too?' added Q.

The Red Knight grimaced. 'Not in the same way. Over there, if you get captured, you just get sent to a POW camp where they try to turn you to fight for your captor's side. I suppose if you aren't going to be required to slaughter your own countrymen, perhaps that doesn't feel like so much of a betrayal, but any Chessman would think being brainwashed like that is a fate much, much worse than death.'

'What's so odd about it?' argued Dog. 'On Othello, people are always going over to the Dark Side and then back to the Light Side, depending on who happens to be standing next to them at the time. It's not so much like a battle, more like conversation where more and more people are won over to the prevailing opinion, just to try to fit in.'

'Yes – that's exactly what makes me feel uncomfortable,' said the Red Knight. 'It's like that old poem about the chameleon: "If that chameleon were I, I'd feel ashamed to sham. At night, all white between the sheets, I'd wonder who I am."'

'What I wonder,' said Q, 'is why nearly all worlds seem to think that life has to be based around competition – that there have to be losers to make the winning worthwhile. I mean, what if Scrabble decided that the object of life is not to earn more points than a rival, but to pave the world with the most beautiful, interesting words possible? What if Cluedonian detectives worked together to fight crime, instead of sharing information only when it's strictly necessary to clear their own names? What if Monopolitans tried to ensure that everyone had access to affordable housing and public transport? For that matter, what if the Othellans started to see the beauty of diversity, instead of trying to achieve peace by enforcing uniformity?'

'That all sounds way too idealistic to happen,' growled Dog, but she couldn't stop her tail from wagging.

'Maybe,' said the Red Knight. 'But if a Monopolitan, a Scrabbler and a Chessman can become friends, anything can happen.'

Author's note: If you're American, you may know Draughts as Checkers, and Cluedo as Clue - but you'd probably worked this out. Also, the chameleon poem is by Michael Flanders.