Swedish journalist Kim Wall boards the UC3 Nautilus submarine with Peter Madsen to conduct an interview for a story she is writing.

The UC3 Nautilus sinks. Madsen is rescued, but Kim Wall is reported missing. Madsen initially claims he dropped Wall off on land the previous evening.

The investigation intensifies as inconsistencies in Madsen's statements emerge. Wall's dismembered body parts are subsequently found at sea. Madsen changes his story multiple times, eventually admitting to dismembering Wall's body but denying murder, claiming her death was accidental. He is arrested and charged with manslaughter.

Madsen's trial takes place in Copenhagen City Court. The prosecution presents evidence of premeditation, including online searches for snuff films and torture videos. The defense argues that Wall's death was accidental.

Peter Madsen is found guilty of the murder of Kim Wall and is sentenced to life imprisonment.

Madsen appeals his conviction, but the Danish High Court upholds the original verdict of life imprisonment.