“It would be like Picasso starting a picture and Matisse finishing it, how would it come out?”, Erland Larsson told AFP, adding that the manuscript was only two-thirds complete.
A crusading journalist who campaigned notably against far-right extremism and misogyny, Larsson’s books have sold two million copies in Sweden and out-sold everything bar the Bible in Denmark.
They have been translated into some 30 languages and a first film adaptation is underway in Sweden.
Larsson did not live to enjoy this success; he died in November 2004 of a heart attack, aged 50, before the novels were published.
His father, who with his other son Joakim holds the rights to Larsson’s works, found the fourth volume in the writer’s desk.
The trilogy follows journalist-hero Mikael Blomkvist in English editions ‘The Girl who Played with Fire’, ‘The Air Castle that Blew Up’ and ‘The Girl with the Dragon Tattoo.’