The door opened and a man walked into the bar, pausing briefly in the doorway to allow his eyes to adapt to the dim light inside. The place was what optimists would euphemistically call a dive. The establishment was empty except for a few drunks and a large, bored-looking man behind the counter wiping glasses with a rag that was presumably once white but was now an indeterminate shade of grey.

The man walked through the room, turned in at a doorway marked “Gents” and scanned the room – two stalls, a urinal and a grimy sink – before spotting what he sought. Moving across the room, he fed a handful of coins into a coin-operated machine advertising cheap cologne. There was a rattle and then a small rectangular device dropped into a waiting hand. The man pushed his thumb against a small pad on the otherwise blank rectangle. A laser washed briefly…