For a debut novel, in fact, for any novel, The Widow by Fiona Barton is a staggering success. It grabs you in the first few pages and just doesn’t let go. In theory it’s the relatively straightforward story of a crime and the ensuing police investigation, albeit dealing with a deeply harrowing subject. A toddler, Bella, has gone missing from her garden during the few minutes she had been left unattended. A media frenzy engulfs the country. In the absence of any immediate breakthroughs, speculation and gossip become the main currency. But slowly, painstakingly, the police begin to piece together shards of evidence which takes them into the dark world of on-line hard-core sex and pedophilia and, finally, a suspect.