‘Alfonse?’ he said out of the side of his mouth. ‘I don’t remember deciding on a name for my character.’

Butler set the stopwatch on his chronograph. ‘I was improvising, Artemis. I thought the situation required it. And if I may say so, you make a very convincing obnoxious teenager.’

‘Thank you, old friend. I try.’

Butler removed an architect’s drawing from his deposit box, folding out the document until it was almost two metres square. He held it at arm’s length, apparently studying the design inked on to the paper.

Artemis glanced upwards at the ceiling-mounted camera. ‘Raise your arms another five centimetres, and take a step to your left.’

Butler did so casually, covering the movements with a cough and a shake of the parchment.

‘Good. Perfect. Stay right there.’

When Butler had rented the box on his last visit, he’d taken numerous photographs of the vault with a button camera. Artemis used these photos to render a digital reconstruction of the room. According to his calculations, Butler’s present position provided him with a ten-square-metre box of cover. In that area his movements would be hidden by the drawing. At the moment, only his trainers could be seen by the security guards.

Artemis rested his back against a wall of security boxes, between two steel benches. He braced both arms against the benches, levering himself out of the oversized trainers. Carefully, the boy slid on to a bench.

‘Keep your head down,’ advised Butler.

Artemis rooted through his backpack for the video cube. Though the box did actually play a computer game, its primary function was as an X-ray panel with realtime viewing. The X-ray panels were in common usage among the criminal upper echelons, and it had been a relatively simple matter for Artemis to disguise one as a teenager’s toy.

Artemis activated the X-ray, sliding it across the door of the deposit box beside