* * *

A few years ago, Lagercrantz, who’d previously published a hugely well-received biography of the soccer star Zlatan Ibrahimović and a novel about Alan Turing, was having a drink with his agent, discussing his career, mulling his increasingly “depressive” work, and wondering whether he was simply better as a writer when he was channeling someone else. He saw his agent’s face suddenly change. Not long after, he was smuggled surreptitiously into the basement of Norstedts Förlag, Larsson’s publishing house, to discuss writing the fourth book in the Millennium series. He walked home in “a state of fever.”

Tasked with dreaming up a new plot for Larsson’s protagonists, the crusading journalist Mikael Blomkvist and the brilliant goth-hacker Lisbeth Salander, Lagercrantz woke at four the next morning thinking about a story he’d done in his reporting days about savants. At the time, the Edward Snowden scandal was in full burn, and after rereading Larsson’s books over a few days, Lagercrantz suddenly had his synopsis: An autistic child who’d never spoken witnessed a murder, whose perpetrators had connections in the tech world reaching all the way to the NSA. He sent it to the publisher, and after a few anxious days received a three-word text message: So damn good. “And then off we went,” he says.

David Lagercrantz (Magnus Liam Karlsson)

For Lagercrantz and his publishers, there had to be a balance between staying true to Larsson’s voice and vision without aping his style too directly. “I couldn’t give Lisbeth Salander three kids and leave them at daycare or anything,” he says. “Lisbeth should be Lisbeth and Mikael should be Mikael. We should feel at home in his universe and with his storytelling. But at the same time, it was very important that I was not pretending to be Stieg Larsson, because that was of course impossible.”

Lagercrantz mentions Christopher Nolan’s Batman trilogy, stating that it’s a huge privilege to inherit such characters, although each new interpreter is bound to have his or her own understanding of the people in play. But at the same time, he believes that some characters, once they’ve reached a level of popularity and public fascination, become concepts that are needed rather than desired. “There are certain characters who we go back to, over and over: the Greek gods, and Sherlock Holmes, and right now we’re obsessed with the superheroes in Hollywood and the Marvel comic figures,” he says. “There are certain characters who we need. Lisbeth Salander is certainly one of them. She changed crime fiction in a way. She’s the girl who refused to be a victim.”

Writing Salander wasn’t easy. In the beginning Lagercrantz exaggerated her too much, making her “a sort of terrible punk warrior,” and giving her emotions that just didn’t fit her persona. Meanwhile, the pressure of replicating such an iconic character only made things harder. “I had nightmares that people would come after me,” he says. But eventually he realized the key was letting the character do, rather than be. “Lisbeth is best in action,” he says. “The hardest thing was to find the introspection.”