The Oslo express is racing across the pre-dawn, frozen pine forests of Norway, wherein sits Detective Inspector Fisk on the last day of Operation Aleppo. He is reading Rafael de Nogales' Memoirs of a Soldier of Fortune.
On page 294, he meets a doomed German soldier in the Middle East who has disgraced his Prussian honour by having an affair with a girl who claimed she was 18 when she was only 16.
General Nogales briefly meets this young man in the German military mess "sometime in August 1915, when I arrived at the city of Aleppo, after six months' steady fighting in the Caucasus".
Odd. Insp Fisk is investigating events in that same city of Aleppo from more than 90 years later, when a Syrian general ordered his soldiers to show me weapons recently captured from the country's anti-Assad resistance.
Among the grenades and rifles was a plastic packet containing three pink sticks of what looked like gelignite, each one was labelled 'Hammargrens, 434-24 Kungsbacka, Sweden'.
Kungsbacka is a small town south of the Swedish city of Gothenburg. Hammargrens, I should add, sells children's fireworks. Thomas Wetterstrom, its managing director, is bespectacled, swarthy, 60 years old and 30 years with the company.
"These are warning flares," he tells me. "I don't really see what the Syrians can do with them. We sell them to the Swedish police." The Swedish police? A bit close to home for Insp Fisk, but true.
Don Kantoff, Hammargrens' explosives officer, asked me if I'd like a demonstration. So we padded out into the sleet; he struck the cap on the top of the flare and it burst into an astonishing pink flame, so bright I could only glance at it for a second.
Kantoff reckons the company had sold 100,000 of these flares in the past 12 years. But, as he studies a picture of the Aleppo haul, he notices the plastic packet: "We stopped using these plastic packets years ago, before we sold to Hungary." He hands me the company's up-to-date cardboard box.
It turns out that, back in 1999 - the date on the Aleppo flares - Hammargrens was selling flares to a Stockholm company, which supplied them to the big Swedish lorry-makers Skania and Volvo.
At this point, Insp Fisk remembered a lecture in Abu Dhabi, in which a Swedish diplomat boasted that Volvo was the biggest exporter of trucks to ... Syria.
Volvo had cornered the market - in pre-civil war Syria, of course - and there was no legal reason why these trucks should not have been sold to Syria with Hammargrens' flares in them.
The story's twist. Everything above board, all sold for safety. But a thought occurs to Insp Fisk.
Sweden hasn't endured a war since 1814. But shouldn't we Europeans be a little more careful what we send to less stable parts of the world? Fewer flares, perhaps?
So, on my train home, I turn again to my soldier of fortune, General de Nogales as the preface crows, "this swarthy soldier of fortune from the high Andes seemed like a chivalrous knight of old ..." Now those were the days.