York author Nuala Casey's follow-up to Soho 4am is a modern tale of four characters adrift in London – with a searing portrait of a young woman battling OCD at its core. STEPHEN LEWIS reports

NUALA Casey once read about a young City worker who became so stressed by her high-pressure life that she jumped to her death from a London office block. Interviewed afterwards, one of the young woman's colleagues said: "This city sucks the life out of you."

That sad story provided the inspiration for York-based Nuala's latest novel of London life, Summer Lies Bleeding.

It follows the lives of four main characters during the hot summer days of 2012. There is Sebastian Bailey, a successful artist; Stella Blake, a thirtysomething young woman who feels trapped in her rural life with her partner Paula and yearns for an academic job at London University; Mark Davis, a northerner down from Middlesbrough scarred by the brutal murder of his sister Zoe a few years earlier; and city analyst Kerstin Engel, a lonely young woman desperately battling with obsessive compulsive disorder (OCD).

The lives of all four are connected in ways they can't possibly know – and they come together in a climax that is shocking, brutal and yet, in a way, almost inevitable.

Summer Lies Bleeding is in part a sequel to Nuala's first novel, Soho 4am. That followed the lives of a group of characters – a wannabe singer; a jazz-musician; a would-be model and a washed-up artist – living on a grimy backstreet in London's notorious red-light district in the hours leading up to the London bombings of July 2005.

Summer Lies Bleeding jumps forward seven years. Stella, the wannabe singer, is now doing a doctorate in English literature, living in apparent domestic bliss with flower-seller Paula in the West Country, but in London for an interview at London University that Paula knows nothing about.

Sebastian, the washed-up artist, is now a big success, his portraits of Olympic athletes plastered all over London during the Olympic games. Zoe, the would-be model, is dead: but her brother Mark has come to London to get revenge on the man – Sebastian – he wrongly blames for his sister's death.

And Kerstin? The only new main character in the book, she somehow becomes the centrepiece. She's utterly alone, utterly cut off from real human contact in the way only someone living in a huge, anonymous metropolis can be. A maths genius, she uses numbers as her protection. Every mistake, every minor disruption in her orderly life, leads to frantic counting in her head as she tries to control her panic.

In one poignant scene early in the book, she notices a small tear in the leather of her purse. It's an imperfection: one that has to be put right straight away. She runs out of the office to buy a new purse, counting off the steps she takes in her head.

"She must keep counting until she gets to her golden number, the number of truth and light, then everything will be all right," Nuala writes. "When she gets to eleven hundred and nine – her birthday, the eleventh day of the ninth month, order and perfection, order and perfection – when she gets to that number then she will stop."

As the novel progresses, Kerstin's counting becomes more and more obsessive – her desperation and exhaustion palpable. It's a searing portrait of someone with OCD – so plausible that you suspect Nuala herself might be a sufferer.

Is she? Talking on the phone from her home in Heslington, Nuala – who grew up near Darlington, lived in London in her twenties, and came to York with her husband Nick and young son Luke in 2007 – bats the question away with a laugh. "We all have elements of it. And I did do quite a lot of research into it: I read a lot around the topic."

Each of the four main characters in Summer Lies Bleeding have convincing inner lives and stories that draw you in.

But it is Kerstin's story, and in particular the contrast between her outer appearance - neat, pretty and well-dressed, the Kerstin seen by colleagues and neighbours - and her inner anguish and exhaustion, that truly haunts you. In a sense, we always know where her journey is going to end. But when it comes, it is still shocking and deeply saddening.

Summer Lies Bleeding by Nuala Casey is published by Quercus, priced £7.99.