William sat cross-legged on the floor behind me with his cars, oblivious to everything. I turned away from him, back to the balcony, and put the camera’s viewfinder to my eye again. A slim figure all in black – black jeans, black jacket, black baseball cap – crossed my field of view. I adjusted the lens but not quite quickly enough as the figure disappeared from sight beneath the first-floor balcony just as they came into focus. I waited for the figure to reappear. Ten seconds, twenty, keeping the camera pointed at the same spot.

A minute went by, and the figure in black still didn’t reappear. The world seemed to go quiet around me. Mel still sat alone at Starbucks, cup cradled in both hands. Her instructions were that she was not, under any circumstances, to look up at the balcony. One glance up here, at me with my camera, and Ben would be gone.

Mel’s phone buzzed in my pocket and I lowered the Nikon. A picture message. An image filled the mobile’s small screen.

It was a picture of William playing with his cars on a blue-and-white tiled floor. Quite close, maybe twenty feet from the camera. In the background of the shot, I could see a tall figure in a blue jacket hunched over a table, camera poised as if ready to take a shot.

I looked down. It was this tiled floor.

The tall figure in the picture was me.

The message read:

Whatever you do Joe keep 1 eye on little William. If he was to wander off I doubt you’d ever find him again

7.56 p.m. Ben mob

My stomach lurched, a flutter of panic.

William –

My coffee went flying across the table as I turned.

His toy cars were there on the floor. His little rucksack.

William, no not that –

My son was there too.

Lying flat out on the floor, rolling a car in each hand.

He’s OK.

I stood up quickly to see if the picture-taker was still there, but saw only two elderly ladies, a cleaner mopping the floor and a lanky teenager talking on a mobile phone. No one who looked like Ben.

The phone buzzed in my hand as another message dropped in.

This time it was a picture of Mel, sitting in Starbucks, pretending to read Metro.

You must think I’m a fucking idiot. Mel + newspaper = epic fail

7.57 p.m. Ben mob

The picture was taken from the same side of the mall as me, but directly below me. Two floors down.

Ben’s here.

In the same building as me, thirty feet of concrete and steel and fresh air separating us.

This was my chance. It was now or never.

I stood up, grabbed my son and ran, slamming through the double doors and hitting the escalator at a run, taking the steps down two at a time as the Nikon bounced against my chest.