It wasn’t Gertrud and Molander, with their cups of coffee and half-eaten apfelstrudel, that interested him; it was the man at the little table behind them. Or, rather, the man’s wristwatch. Its hands showed quarter to nine, and judging from the light and the prevalence of coffee cups rather than wineglasses on the tables, it was before noon.

In another picture from the same day, Gertrud was standing with her glasses pushed up into her hair, studying a tourist map in something that looked like a hotel lobby with clocks showing the time in New York, Tokyo and Berlin. The hands showed eleven minutes past seven, which was probably just before they left for the café.

There were three more pictures from 24 August. In one, they were posing in front of the bombed church spire rising from the asphalt, roofless and hollow, a reminder of how present the Second World War still was in the German capital.

The only thing that looked renovated was the clock face, which shone like newly polished gold, in sharp contrast to the sooty stone façade. Its hands showed twenty past nine, and here, there could be no doubt it was in the evening. Both Gertrud and Ingvar were now dressed up for a fancy outing, having shed the windcheaters and ergonomic shoes they’d been wearing that morning. She wore a purple evening gown, high heels and a leather jacket, he a blue suit with a bow tie and patent leather shoes.

In the second picture, they were sitting at a bar raising their cocktails to the camera, and in the third, they were eating plateaux de fruits de mer in a restaurant. The rest of the pictures were from the other days and showed them doing touristy things in Berlin.

The pictures more or less documented their days from morning to night and were taken reasonably regularly, no more than a few hours apart. At least as far as Thursday night, when they arrived, Saturday and Sunday were concerned. The Friday, on the other hand, was a different matter. It had a gap of no less than twelve and a half hours. Between the café visit at quarter to nine in the morning and twenty past nine in the evening, there wasn’t a single picture.

What had they been up to during all those hours?

Granted, it was their anniversary, but he found it hard to believe they’d spent the whole day between the sheets in their hotel room.

He clicked over to Momondo and did a search travelling from Berlin to Copenhagen and back on a random Friday in August. The list of departures showed that the route was primarily served by SAS, Norwegian, easyJet and KLM. Norwegian had no flights under four hours since their routes required a stopover in either Stockholm or Oslo, and KLM didn’t have a single flight in the twelve-hour window.