S10E04: Draw the curtains and dim the lights for a chilling trip north for a documentary which investigates the success of Scandinavian crime fiction and why it exerts such a powerful hold on our imagination. The Girl with the Dragon Tattoo is a literary blockbuster that has introduced millions of readers to the phenomenon that is Scandinavian crime fiction - yet author Stieg Larsson spent his life in the shadows and didn't live to see any of his books published. It is one of the many mysteries the programme investigates as it travels to Denmark, Sweden, Norway and Iceland in search of the genre's most acclaimed writers and memorable characters. It also looks at Henning Mankell's brooding Wallander series, with actor Krister Henriksson describing the challenge of bringing the character to the screen, and it asks why so many stories have a political subtext. The programme finds out how Stieg Larsson based the bestselling Millennium trilogy on his work as an investigative journalist and reveals the unlikely source of inspiration for his most striking character, Lisbeth Salander. There are also segments on Jo Nesbo, the Norwegian rock star-turned-writer tipped to inherit Larsson's mantle, and Karin Fossum, an author whose personal experience of murder has had a profound effect on her writing.