It is Monday August 13th 2012, the morning after the closing ceremony of the Olympic Games in London. The city is relaxed as rarely before, delighted with itself at how spectacularly - and how securely - it has hosted the uplifting event.

The capital, however, will be rudely and brutally awoken from its self-congratulation by a horrific attack perpetrated by a young man who enters unchallenged the London Central Mosque in Regent's Park and burns to death with a flamethrower five Muslims in the prayer hall.

How could it happen? Why did it happen? Is the atrocity political, religious or personal?

THE OUTER CIRCLE - which has at its core a focus on relationships amid the cultural concerns of modern Britain - follows five people caught up in the event and its aftermath of anxiety and reprisal as the story unravels over the next five days.

They are:

Saul Bradstock, a 59-year-old semi-retired book editor, living alone in Primrose Hill and undergoing radiotherapy treatment at the Royal Marsden Hospital for prostate cancer.

Tom Judd, 25, a musician and languages graduate from Birmingham. How did he get to Regent's Park, why does he look so lost and what is he doing sleeping rough in the undergrowth?

Rashid Johnson, a 23-year-old working in the Mosque's bookshop. Raised a Jew in Stanmore, North London, and secretive about his recent past, he has not long 'reverted' to Islam.

Deena Campbell, 19, a policewoman based at Paddington Green and native of South London, where she lives with her parents, whose own parents came to England on the SS Windrush.

Jan Mason, 42 years old, single, living in a flat in Maida Vale and just about clinging on to her job as a news reporter for a mid-market national tabloid newspaper.

As the hottest week of the year unfolds, fate will throw the five together, along with a strong supporting cast of family members, police and the media, until a dramatic Friday denouement in Regent's Park