And here it is: her birth certificate. I find myself reading it holding my breath.

Here they are, the names of her parents. Suddenly they are a hundred times more real. Sarah’s mother, Sarah’s father. I’m getting closer, step by step. I plug their names, together now, into my search. The database works hard for me, offering up new leads.

Now a marriage certificate appears. And with it, an address. The place where, back then at least, they lived. Somewhere a long way away from London.

My brain feels as though it’s tingling. My whole body is tense, on edge. Through this database too, you can find other addresses. You can check the other places people have lived – still live. It’s a function I’m not technically licensed to use. Maybe the police never even went this far. But these are exceptional circumstances, surely. And if I don’t tell anyone that I’ve looked, who would know?

I tell myself I’ll only look so far. There are other searches I could run, other databases, even. But I won’t. I’ll go as far as I can here, then I’ll stop; I’m already stepping over a line. Even with this one address, it might be enough. And in fact, when I run their names through this feature, no other homes come up. Which means the address from the marriage certificate is where they’re still living – unless, of course, they’ve moved out of the country: Scotland, Northern Ireland, Wales or abroad.

My hands are shaking as I log out of the database. I’ve only been in there two minutes at most. Now I plug the postcode into Google, a search engine anyone’s entitled to use. When the map appears, I click straight onto Street View. The stretched images appear, disorientating at first, but then I spot the road sign: I’m in the right place.

I scroll my way up the road, checking the house numbers. It looks like such an ordinary street: the houses on either side are uniform, modest. It looks as if such ordinary people live there. Is this where Sarah used to visit them? You can go there, I think. You could knock on their door. It’s not impossible. Not a totally crazy idea.

The Street View is glitchy, every transition a jerk. Thirty-five, thirty-seven. I need forty-one. When I reach the right place, though, I can’t believe it. I have to scroll back and forth to check. Number thirty-nine is there on one side. And there’s forty-three, but …

Number forty-one should be right in between. Instead there’s nothing. Only a blank. A flattened plot of land that someone’s tried to concrete over.

This is where they were supposed to be living.

Instead Sarah’s parents’ house has been torn down.