The Doppelganger writer and winner of the Women’s prize for nonfiction on the war in Gaza, current credibility of the left and posters for her book being torn down in London

The night before Naomi Klein won the inaugural Women’s prize for nonfiction, she discovered that someone had been going round London tearing down posters advertising her book. “And the weird thing is, I didn’t know what had angered them: vaccine disinformation, Zionism, or climate change and Fossil Free Books,” she told the assembled crowd.

Klein’s winning book, Doppelganger: A Trip Into the Mirror World, is an analysis of shadow identity that opens with a riff on the infuriating, longstanding confusion between the author and feminist turned conspiracy theorist Naomi Wolf. It ends with a deeply felt meditation on the mirroring of victim and persecutor evident in the current war in Gaza.

Judges praised Klein’s Doppelganger for its ‘courageous’ study of truth in politics and called Ganeshananthan’s Brotherless Night a ‘masterpiece’ of historical fiction

Doppelganger by Guardian US columnist Naomi Klein has become the inaugural winner of the Women’s prize for nonfiction, while Brotherless Night by VV Ganeshananthan has been named winner of the fiction prize.

Both books look at how people get swept up in extremism: Doppelganger uses the fact that Klein is regularly confused with feminist turned conspiracy theorist Naomi Wolf as a jumping off point for an exploration of truth in politics, discussing populist figures such as Steve Bannon and Donald Trump. Meanwhile Brotherless Night, mostly set in Jaffna during the Sri Lankan civil war, is about a girl who dreams of becoming a doctor before war breaks out in her country and those around her begin to engage with violent political ideologies.

Brotherless Night by VV Ganeshananthan (£9.99) and Doppelganger by Naomi Klein (£25) are both published by Penguin. To support the Guardian and Observer, order your copies at guardianbookshop.com. Delivery charges may apply.