Healthy cows were directed to one doorway, sickly to another. Both were slaughtered for meat but the tainted ones were sold locally to the poor in Hell’s Kitchen or shipped down to Five Points or the city of Brooklyn, for the filthy markets there. The more robust cattle ended up in the kitchens of the Upper East- and Westsiders and the better restaurants in town.

Billy didn’t know which of the exits was for the healthy beef, which for the sickly. He’d been down both until they ended, one in brick, one in rubble, but he couldn’t deduce which was which. He wished he knew because he wanted to tattoo the young lady in the tainted beef corridor – it just seemed appropriate. But he’d decided to do his mod in the place where the livestock cull had been made: the octagon itself.

He looked her over carefully. The tattoo was good. The cicatrized border too. He was pleased. When he did a work for clients in his shop back home, Billy never worried about their reaction. He had his own standards. A job they seemed indifferent to might fill him with ecstasy. Or a girl could tearfully look over her wedding cake tattoo (yes, pretty popular) and cry at how beautiful it was but he’d see one flaw, a tiny stroke out of place, and Billy would be furious with himself for days.

This art was good, though. He was satisfied.

He wondered if they’d catch on to the message now. But, no, not even Lincoln Rhyme was that good.

Thinking about the difficulty he’d had earlier – at the hospital and the doctors’ office building – he’d decided it was time to start slowing down those pursuing him.

One of the passages in the Commandments, written in Billy’s flowing script, was this: ‘Continually reassess the strengths of the officers investigating you. It may be necessary to throw up roadblocks to their investigation. Aim for the lower-level officers only; too senior, and the authorities will bring more effort to bear on finding you.’

Or, in Billy’s terms: Thou shalt smite all those who are trying to mess with the Modification.

His idea for slowing them down was simple. People who’ve never been inked think that machines use a hollow needle. But that’s not the case. Tattoo needles are solid, usually several soldered together, allowing the ink to run down the shaft and into the skin.