I look around. The walls are painted an anodyne cream, lending the room a hospital-like air. Pinned alongside framed pictures of Bush and Cheney are various notices on immigration, the simian features of an FBI most wanted and warnings of the dire penalties of drug smuggling. A dozen people are waiting to be seen, all Mexican. A young couple holding hands. Two wrinkled men in cowboy hats and a teenage boy who leers at us with the burning, unblinking eyes of a junkie. A thickset Mexican with a shaved head and ears like kidney bowls stomps by, trousers tucked into black military boots, his navy uniform straining over every inch of his body. A walkie-talkie strapped to his waist crackles with some kind of code. ‘Three-twenty activity . . . south . . . two-seventy . . .’

Our friendly official reappears and asks me for picture ID and I go through the whole story once again. Agent Harrigan, I read off his badge.

‘Not even for the kids?’

‘Nothing. I’m sorry.’

Is there anyone I can call, he asks, who will bring the passports to Nogales? And I think of Benjamín, but even if I had the capability of reaching him, I have no idea of his exact legal status.

‘No.’

He returns to the telephone. I haul Jack onto a chair and slump down in the empty seat next to him, Emmy heavy in my arms. I watch the clock as fifteen minutes pass, then another fifteen. Emmy’s eyes flutter open. ‘Mummy, Mummy,’ she says, ‘I want you to buy me a blanket a soft one for a five-year-old girl like me and I want you to give it to me so I can sleep with it and cuddle it and not be scared so much any more.’ I look down at her dirty face, at the tiny clusters of broken veins visible beneath her skin and shake myself into action.

Agent Harrigan is still on the phone.

I poke my finger in his arm. ‘Excuse me, what’s happening?’

He holds a finger to his lips, but I am not to be shushed.

‘Look, there must be a system for a situation like this. What do you do with people who’ve had their passport stolen, for instance?’

He places his hand over the phone. ‘Your passport hasn’t been stolen, ma’am. This is a case of wilful violation.’

Wearily I begin again. Emmy’s fit, my headlong panic, the passports being left at home. I describe their exact whereabouts – on the bookshelf in the bedroom – hoping that the sheer mundanity of detail might reassure him. But no. I try to keep my cool, to control the prickle of sweat breaking out over my body. I try to convince him that if he will only let me go home, I can myself fetch the passports and bring them back later on in the day.