In extremis: The turbulent life of Marie Colvin

"She would go in further and stay in longer," said Hilsum of Marie Colvin, the Sunday Times war correspondent. "She really cared about the people she reported on."

Her biography, In Extremis, tells the story of her trajectory from young American school girl to the tenacious, determined journalist in some of the world's most dangerous war zones. From Syria and Sri Lanka to Kosovo and East Timor, she covered conflicts through the lens of human suffering. "Most of the journalists left East Timor because it was incredibly dangerous," said Hilsum, "Marie had no intention of leaving."

Her friendship with Colvin was one formed on the frontline. Hilsum said she used to think: 'if Marie is here then this is the right place' to be as journalist.

Colvin was killed in Baba Amr, Syria in 2012. Six years later, an American judge determined she had been murdered. “She was specifically targeted because of her profession," said Judge Amy Berman Jackson, "for the purpose of silencing those reporting on the growing opposition movement in the country."

The biography, however, is more than a tale of war and death. Hilsum documents Colvin's personal life; from her happiest moments to her darkest hour. "There were a lot of demons and she was very haunted by what she had seen."

"She's so human. She is so flawed," said Hilsum. "Of course, she lived in extremis... She had those fears, worries and heartbreak that we all have."

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Photograph by Chris Athanasiou