‘Juliette told me that F-287, or Frank – that’s the dead bird above the fireplace – carried a map, infantry locations, coordinates and other vital information across enemy lines. But, even in code, the map alone would be enough to weigh down a bird. I didn’t realise that your father had framed the actual life-saving message too, Juliette.’ I held the loupe underneath the medal, where the small slip of paper with the meaningless dots on it had been mounted. It was obvious, even without peering into the lens itself, that it was magnifying out of the tiny dot a detailed map. We’re moving into le Carré over Christie here – ‘spy shit’ as my father called it – but stick with me. Though my how-to book on it hadn’t sold very many copies, it was about to pay dividends. ‘They’re called microdots. It’s a technique used to shrink information. An entire A4 sheet of paper, or an image, like a map, for example, can fit on a dot the size of a full stop. Spies were quite fond of these in the Second World War – they’d put them on the back of postage stamps. This’—I held up the loupe again—‘was rattling around in Michael’s car when he buried Alan. He also brought it with him here. Erin took it when Crawford arrested him. It’s a jeweller’s magnifying thingy.’ (Remember, I only learned the word ‘loupe’ while writing this book, so it would be disingenuous to fake my dialogue.) ‘Marcelo, your watch, the real one, had a microdot under the glass. Robert never used drugs. The needle they found on his body, which led to the conclusion that he was high and trying to stick up a petrol station, wasn’t for injecting. Microdots are so small that I assume you need something fine like a syringe or the tip of a pen to apply them to a surface.’

I held up the loupe.