On Thursday afternoon, freelance journalist Kim Wall stepped aboard the UC3 Nautilus, an imposing, privately built, black submarine docked in the Port of Copenhagen.
The 30-year-old Swede was there to interview its owner, a Danish inventor named Peter Madsen – an eccentric man famous for building the sub via crowdfunding in 2008, and for his company RML Spacelab, which plans to be the first to launch a human being into space in an amateur-built rocket.
But by Friday afternoon, the 46-year-old man was being winched to safety by a nearby boat as the Nautilus sunk to the depths of Koge Bay. Technical issues, he claimed; a “minor problem with a ballast tank”, he told local station TV2.
But with Kim Wall nowhere to be found, authorities had their suspicions. Suspicion enough that, on Saturday, Madsen was charged with manslaughter.
So what happened that evening?
Kim Wall boarded the submarine at around 7pm on Thursday, reportedly to conduct an interview for Wired Magazine. There are photographs - the last known to have been taken of the Swede - that show her standing with Madsen on the vessel's tower that evening, looking out to sea.
According to a police spokesman, Madsen claimed to have dropped the journalist at Refshale Island at 11.30pm. However, her boyfriend reportedly alerted police on Friday morning that she hadn't returned.
A wide-scale air, land and sea search has so far failed to locate the missing woman.