He woke with a start two hours later when the landlady knocked on the door. ‘Would you care for a cup of tea, Mr Minh?’ she called.

Nguyen thanked her but said no and she went back down the stairs. He sat up and rubbed his eyes. The curtains were blowing into the room and the sky was darkening outside. He slid off the bed and turned on the light. There was a lamp on the dressing-table and he put it on the floor, under the window, and pulled out its plug from the mains. He spread a newspaper on the shiny wooden surface and then took the soldering iron, solder, flashbulbs and wire and put them on the newspaper. He plugged in the iron and while he waited for it to heat up he used the Swiss Army knife to cut twelve sections of wire, each about eighteen inches long, and then stripped a short section of plastic from the end of each piece. He soldered a wire to the bottom of each of the flash-bulbs, and another to the side. He used a battery to test one, touching the ends of the wires to the two terminals. It burst into white light and hissed as it melted. He tossed it on to the bed.

In Vietnam they’d had a plentiful supply of blasting caps, but they were hard to get hold of in peacetime. Not that it mattered, because the home-made explosive was sensitive enough to be detonated by a flash-bulb. Nguyen had decided he would make extra sure. He opened two boxes of matches and emptied them on to the newspaper. He stripped off the red heads until he had a pile of several dozen and then he crushed them with the blade of his knife, one at a time. Occasionally one would burst into flames as he worked and he’d use the blade to extinguish the fire. When he’d finished he had a neat pile of red powder. He smeared glue over the bulbs and then rolled them in the powder until they were completely covered. He left them to dry on the newspaper while he prepared the plastic piping. It was the sort used as drainpipes in cheap housing. He’d cut each piece with a hacksaw so that they were about a foot long. He sealed up one end of each pipe with strips of insulation tape and then took them into the bathroom. He put his gloves back on and half filled each pipe with the explosive mixture, then went back for six of the detonators. He held the wires in his left hand as he carefully eased the sticky mixture around the detonators, two for each pipe, and pressed it down. When he’d filled all three he sealed the ends closed with tape with just the wires protruding. They looked childish and inelegant, but Nguyen knew how deadly and effective they were. Properly planted in a road, they could destroy a car and leave a crater more than six feet across. All that was needed to set them off was to pass an electric current through the wires.