Anne Dixey was a perfectly normal working mother, a producer on Radio 4's PM programme in London, when she was plunged, not entirely willingly, into a new life as a mum and homemaker in American suburbia.

Worse, as Dixey arrived at her home in Montgomery County, Maryland, the hijacked planes hit the World Trade Centre and the Pentagon. She lost contact with her partner and, later, two FBI men arrived to question her.Then, in quick succession, there was an anthrax scare at a local post office, and a sniper began shooting people on their lawns and at garages.

Dixey went to America in August 2001 with her two children and partner, Roland Watson, the Times' Washington correspondent. She gave up her job, but planned to freelance. Instead she ended up on the home front, mostly alone, in an increasingly strange country in the aftermath of September 11.

When the planes hit, Dixey was with her two-year-old, Josie, and had just taken her four-year-old, Amalie, for her first day at nursery. Suddenly, the phones went down and Watson was 1,000 miles away in Florida. He drove for two days to get back to Washington, filing reports from roadside motels, behaviour that the FBI considered suspicious in the nervous climate.

At Dixey's house among the white clapboard and verandas of Chevy Chase, Maryland, the Stars and Stripes began to bristle on lawns, and the talk was of war and bioterrorism, instead of little league softball. Yet the community was warm and welcoming; new neighbours arrived bearing fresh raspberries - and frozen vodka and orange juice to calm nerves.

The neighbours soon became fast friends. “Yet it seemed a bad dream at points,” says Dixey, now 43. “I was trying to get to know people, but I kept thinking ‘this can't be normal'. It was so extreme, the constant fear of what would happen next. Americans around me were hysterical: there was none of that calm British getting on with it.”

Eventually, Dixey decided that her weird experiences merited writing a book, The United States of Hysteria. “It's sort of a home movie through the white picket fence, through the eyes of a foreigner. We do have this national fascination with all things American - but I realised that we had no idea about ordinary people's lives.”

On the surface, life was wonderful: picnics, bike rides, new friends, blue skies, constant sunshine, “so perfect you know it couldn't be real”, says Dixey. As a small, short-haired vegetarian “who wears too much black” she knew that she was never going to fit right in.

After a tense first year, Dixey was just settling down, volunteering at Josie's school, when a call came to say that five people had been shot by a sniper in Montgomery County. Later a 13-year-old schoolboy was shot too. “I felt the two worlds colliding: the safe, suburban bubble and the other violent world of guns, drugs and gangs.” The Washington area is strangely segregated. “It was shockingly unmulticultural for a city that was two-thirds black.

“It is extraordinary that DC is the seat of government and black children are regularly dying two miles from the White House. Yet no one pays any attention. The American people deserve better.”

The sniper was eventually caught. “But in Britain, there would have been a public inquiry about gun laws; in Maryland, a pro-gun Republican governor was voted in over Kathleen Kennedy Townsend, and he brought back the death penalty for good measure.” Dixey points to the extraordinary statistics: Washington, one city of 500,000 people, had 137 gunfire killings last year, compared with 59 shot in the whole of England and Wales.

Dixey shrugs, now back in the family's flat in Shepherds Bush, London. “I made some fantastic friends in Washington but I was shocked by the conservatism with a small ‘c'. There was so much emphasis by parents on re-creating the ‘perfect' childhood they'd had. I'd expected it to be more civilised and cultured, but there was limited conversation, politics, and the War on Terror.” Even Washington's local sport, indulging in political gossip at dinners and embassies, was out: “Politicians couldn't be seen to be partying while the nation was in trauma.” Meanwhile, at home, Dixey was often faced with the “supermoms”.

Flexible or part-time working just didn't seem possible. It was all or nothing, there was no slack so these very intelligent, highly educated women approached motherhood as though it was a career. In Washington you are what you do. When you stop doing something, you become your partner's accessory. “There were all these women who had been to Harvard and were better qualified than their husbands, looking after their children, volunteering, and they weren't recognised enough for that.”

Dixey is amazed by this in the country that first embraced feminism, or as Betty Friedan wrote in 1963: “Each suburban wife struggled with it alone. As she made the beds, shopped for groceries, matched slipcover material, ate peanut butter sandwiches with her children, chauffered Cub Scouts and Brownies, lay beside her husband at night, she was afraid to ask even of herself the silent question ‘Is this all?'”

It was not enough for Dixey, and she is happy to be back working in London. In a strange run of ill-luck, Dixey and Watson returned to Britain just after the 7/7 Tube bombings. “There was quite a different reaction here, less hysterical. But I was still very glad to be home.” Shepherds Bush was dusty, cramped, and polluted.

And much less friendly. “I'd never have met any of my London neighbours if there hadn't been a gas leak in the street and everyone was moved into a hotel round the corner. It was great fun. That's the only way we all got to know one another. A street party would never have worked.”

BOOK EXTRACT: 'It's like being an extra in a psycho killer film'

Today, as well as an armed policeman, there is a police car with flashing lights at the school entrance. More and more sirens go off in the distance. “You used to think it was a fire or a car accident when you heard that,” says one mother grimly. There has been a shooting in DC, someone just heard on the radio. Could it be connected to previous shootings in the area? Or just another drug-related crime on the wrong side of town, the kind that no one used to take much notice of? “What did you do in school today?” I ask Amalie on the way home, trying to keep things normal. “We did a poem about how to dial 911 in an emergency,” she replied. “What else?” I ask. “We made a puppet of a fire chief out of a paper bag. And we wrote a book called Blue Land about a place where everything was blue.”

Police chiefs in Prince George's County, Montgomery County and Washington DC have asked for Federal government help. A killer is still on the loose and the world is watching. The radio says that schools in Montgomery County, Prince George's County and Baltimore County are in lockdown. Afternoon kindergarten is cancelled. Parents of children being picked up must have photo ID. It is day seven and there have been nine shootings and six deaths - in shop car parks, at petrol stations, a bus stop, and the school gates. One victim was mowing a lawn. Just normal people going about their everyday lives. The older kids have had to give up the coveted job of crossing patrol for now.

Today, parent volunteers stand on the corner of every road on the route to school, like a guard of honour. More parents than they needed have offered, one of the dads says. Other volunteers will be helping in the classrooms, providing extra distractions for restless kids. “I kept my kids at home today,” Gail later confesses on the phone. “I can't stand it.” The next day, a man is shot at a petrol station in Virginia. It is like being an extra in a psycho killer film. Two days later, while the girls are safely locked in school, I interview customers at petrol stations for a newspaper piece. Flowers are at the spot where Lori Ann Lewis-Rivera was killed while vacuuming her van on a weekday morning.

Everyone is trying to be rational. “When your number is up, your number is up,” the customers say. These are the brave ones, but even they are crouching behind their cars and glancing over my head, looking for white vans. No one wants to talk for long. As I chat to mechanics in a garage shop down the road, pictures flash up on the TV of a new shooting at another petrol station in Virginia. Another death. They shake their heads and get back to work.

While our children hurl themselves around Leah's secluded back garden, she and I discuss whether or not it is responsible to take your kids to the petrol station. “What if you make them stay in the car and lie down?” I suggest. We sit in silence for a moment, hardly believing that we are having this conversation.

It is revealed that a tarot card was left at the scene of a shooting. It read: “Dear Mr Policeman, I am God.” A woman was shot dead yesterday evening as she loaded her car at a busy shopping centre in Northern Virginia. The gunman (no one suggests a female) escaped again.

The park is deserted. Parents and carers park their cars and briskly take the children to and from the nursery school door.

Sherri down the street shakes her head, glancing at the empty trampoline that usually has children bouncing on it. “It's like living in Beirut for these kids, locking them in,” she says. At first we keep it vague in front of the kids. “I expect the teacher said you had to stay in for recess because there was a storm coming.” But children talk. “Do you know why we are locked in at school, Josie?” Amalie asks her sister. “Because there's a bad man who wants to hurt kids.”

It can't be good for you, living like moles. But whose mental health is most at risk, the adults or the children? A man survives a shooting outside a diner in Virginia. The sniper leaves another “I am God” note. The letter also says: “Your children are not safe anywhere or at any time.” There are more tarot cards. He is clearly insane. Yet the combined might of several police forces and the FBI has failed to catch him.

Now a bus driver is shot dead in Aspen Hill, Montgomery County. It is getting closer again, eight miles away. It is day 21. Some police arrests quickly turn out to be a false alarm - illegal immigrants trying to get money. They have a footprint here and a tarot card there to go on. The police are trying to talk to the killer. It feels like a dangerous game. At pick-up time, a policeman in a “SWAT team” T-shirt races past the school entrance to his car to catch the radio. Another, in plain clothes, stands at the door watching.

After school and nursery, we take it in turns for classmates to play at each other's houses - at least then they see a different back garden or a different living room. Now, no matter who comes, it is the same awful game. The children pull down all the blinds, turn out the lights and lie on the floor under the table in the dark. The Montgomery County Public Schools website confirms that Code Blue security restrictions are continuing. There will be no outdoor recess or physical education. All field trips, regardless of destination, are cancelled. Schools will continue to keep exterior doors locked and monitor visitors. There are tips for adults on how to cope with cumulative stress.

The school has suggestions for “what children can do about terrorism”. These include: “Make a fear box. Cut out pictures from newspapers and magazines about what frightens them. Write down their fears and put them inside.” Or “Put together a peaceful box. Ask kids to find toys, stuffed animals and pictures that make them feel safe and peaceful and keep these items in the box.” On the evening news, pictures suddenly flash up of the FBI digging up a garden in Tacoma, Washington state, on the West coast. Later, an arrest warrant is issued for a former soldier and an unnamed young man believed to be with him. Police have also given a description of a blue Chevrolet Caprice. Not a white van, then. Everyone is glued to the news, desperate for an arrest. We wake up to hear that two men were arrested in a rural lay-by in Maryland during the night. The sense of relief is overwhelming. Everyone is smiling today, stopping to chat, savouring the chores of going to the supermarket and filling up with petrol. The children are ecstatic, running round outside like mad things, free at last.

©Anne Dixey 2008. Extracted from United States of Hysteria: An Englishwoman's Journey through the Madness of America, published by mondaybooks.com, £7.99. Available for £7.59 from Times BooksFirst, 0870 1608080; timesonline.co.uk/booksfirst

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