In a cramped basement flat in Moscow, a beautiful young Norwegian woman is watching her first images of war on a black and white television screen with her Russian hosts. There are images of charred bodies, the outlines of children frozen into the ground and burnt-out tanks.

Asne Seierstad, only 24 at this time, is just starting out as a free-lance journalist. She writes rather confused dispatches based on the television images, learns how to spell “Chechnya” and finally decides she has to go there to understand what is really happening.

Talking her way onto a Russian military aircraft heading south, she sits on a folding seat between two pilots who will soon be bombing Chechen rebels in ravines and mountains, mostly hitting civilians.

With incredible courage, Seierstad then spends most of the next year reporting on Russia’s dirty war from the viewpoint of both Chechen families and fighters. She also narrowly avoids being raped by a soldier with a Kalashnikov.

That all happened 12 years ago. The book that she has just written – The Angel of Grozny, published this week – is about both her first experience of war and her return to the brutalised city a decade later.

This time, she slipped illegally into the Chechen capital and took up residence in an orphan age run by a woman called Hadijat – her “angel” – with a flock of traumatised street children.

Why did she go back? In the years since she first went to Chechnya, Seierstad has grown rich on the proceeds of her surprise international bestseller, The Bookseller of Kabul. She is tall, beautiful in a blonde-haired Scandinavian way, and could easily afford to drink mojitos under palm trees for the rest of her life.

So why spend months sharing a bedroom heated by a gas stove with an elderly Chechen woman, eating communal meals of bread and soup? Why risk her life in a place where just venturing onto the streets can be fatal? And why expose herself to horrifying tales of abuse told by the children in Hadijat’s orphanage?

“I felt it was my duty to go back,” Seierstad says in crisp English that carries only a trace of her native Norwegian. “Chechnya had been forgotten . . . this hidden place about which Vladimir Putin [the Russian president] was controlling the flow of all information. I had an advantage – contacts, language, patience. There, I thought, I can make a difference.”

Bizarrely, she was based in a small town in Ohio in 2005, writing a book about America, when she suddenly had the urge to return. The catalyst was a friend’s photographic exhibition in Norway that showed images of Chechnya. Seierstad, briefly back in her home country for a wedding, found that the photos brought all her memories flooding back. Instead of flying back to the US, she returned to Chechnya.

During her first visit to the country, she was surprised at the extent to which she was personally affected after just a few weeks. “There was a fragment of mirror glass above the sink,” she recalls. “I saw eyes there. The eyes were filled with fear and horror. Then I realised they were mine and I was so shocked.”

One day she ventured out in a car, which then came under fire. She tumbled out of it into a ditch and, desperately happy to be alive, ran to a Russian checkpoint. There, a young Russian soldier, stinking of vodka and stale sweat, waved his Kalashnikov at her, yelling that she and her companions were under arrest. Then he told her he wanted to take her alone into the woods, claiming it was a short cut to headquarters, and aimed his gun at her stomach.

Seierstad heard a tank coming down the road. “I tore myself from the soldier’s grip and began shrieking and howling and waving my arms. ‘I don’t want to go into the woods!’ I was thinking. “ ‘Tears, tears, scream for mama, scream that you want to go home, scream anything at all!’ I remember thinking. ‘I can’t leave this checkpoint because what will happen in those woods will be terrible.’ Even if he put a gun to my head, I was not going into those woods.”

The tank stopped, and she was saved.

With her striking beauty, it became imperative for her to learn how to frown and look unfriendly when she went outside. Her first war – she has covered others since – undoubtedly marked her. “When I went back to Moscow to recover, I became depressed. I had lost my drive: I just wanted to go back again. Real life was in the mountains in Chechnya, where people were waging a life-and-death struggle.”

On her more recent trip, she tried to teach English to the traumatised children in the orphanage. Among them was Leila, who had been raped for years by her drunken uncle after her parents were killed by the Russians. Leila was unable to stop stealing, even though she was now safe, and regularly filched the week’s bread money, spending it on ice-cream cones for the younger children.

Seierstad has now funded a bakery next door. “Maybe Leila can become a baker. Maybe she can be the best baker in Grozny,” she says.

Since returning to Norway, Seierstad has become pregnant for the first time – by a jazz saxo-phonist called Trygve Seim, the first man she has ever been serious about. That was 4½ months ago. “We still call the baby ‘it’,” she says, laughing. “I want it to grow up in the same way that I did: to trust in yourself.”

She is nervous about revealing her pregnancy. The Norwegian press has pursued her since The Bookseller of Kabul made her not only a bestselling international author but the biggest-selling nonfiction writer in Norwegian history. When Shah Mohammed Rais – the bookseller of Kabul himself – flew to Oslo to launch a legal action against her because he didn’t like the way she’d portrayed him and his family, his arrival caused a sensation.

Before her book was published, he had been viewed by many as a liberal intellectual who had saved many of Kabul’s books and manuscripts from the Taliban. But when Seierstad lived with him and his family, she saw first-hand how badly he treated his family.

Part of the fallout from Rais’s protests was a barrage of criticism from other foreign correspondents – but Seierstad is the kind of woman some people love to hate. She speaks five languages, is “okay” in four and has studied in France and China. In person, however, she is open and self-deprecating.

She says she didn’t write about the big picture in Chechnya “because other people do that better than me. I wanted to write about what I saw”. And what she saw was nearly always heartbreaking. She tries to “put armour” around her emotions now she is back home, but clearly needs to guard herself carefully. “We had mice at home in our basement and a company came and put down eight traps,” she tells me. “But I couldn’t bear to see the little mice trapped and dead.”

She has, of course, seen much worse things in war – “children with stomachs torn open, people who are not going to survive” – but she knew she could not cope with even a few dead mice in the place she identifies with safety. “I just couldn’t risk having that image in my head,” she says.

The Angel of Grozny: Inside Chechnya, by Asne Seierstad, is published by Virago Press on March 6 at £14.99

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