Set in the British city of Leeds in the present day and 1975 (the year the Yorkshire Ripper was starting his spree), the story revolves around the murder of a prostitute, lost children, seedy sorts giving the cops plenty to do, a dark secret known only to a few (mostly bent policemen) and a series of coincidental events that form links among the disparate cast.

Although this is officially a Brodie mystery, the story really belongs to cynical former police officer Tracy Waterhouse ('Tracy had seen all the 'ps' - paedophilia, prostitution, pornography'). Tracy is an unlikely hero who thinks the world is after her, but, 'poor old Trace' doesn't know that luck is on her side.

A single woman in her 50s, childless, 'a big, graceless girl' with a penchant for Viennese truffles and crisps, Tracy is now retired from the force and working at a shopping mall as a security officer, musing sadly on how different things could have been.

After a brief introduction to the scene of a murder in the 1970s at which Tracy was present, the story unfolds in the present day. Tracy - on her shift at the Merrion Centre - comes across Kelly Cross ('A scrag-end of a woman'), a prostitute and drug addict with an unknown number of fostered out children.

Kelly is roughly dragging a child across the centre, much to the horror of onlookers, as the little girl known as Courtney (As Tracy says: 'Courtney - typical chav name - Chantelle, Shannon, Tiffany, Courtney.') tries to sing Twinkle Twinkle Little Star. This affects Tracy in more ways than one ('The kiddies,' she tells a colleague when talking about what gets to her most) and in a split second decision, Tracy makes an inpulse buy. It seems a fair thing to do (albeit illegal).

From that moment of madness Tracy's life goes into a whirlwind peppered by guilt, joy and chance encounters with thugs she thinks are chasing her. Through flashbacks to the 1970s, we also learn how one crime more than 30 years ago has influenced Tracy and her former colleague Barry and is the reason why Brodie is on the scene.

In the background there is much more sinister activity at play, including two thugs on Brodie's tail (he is working for an adult adoptee seeking her real parents), a former social worker gone missing, Tilly the ageing television actress suffering from dementia and - confusingly - another private detective called Jackson.

The chance encounters and coincidences could make this all seem ridiculous but, thanks to Atkinson's richly layered characterisations and clear-cut motivations, their behaviour doesn't seem that harebrained.

A mish mash of hilariously inappropriate 1970s-isms about race and women, 'lowest common denominator' television programmes of the present day and Brodie's own dog-snatching moment, combine to create a quirky portrayal of damaged lives, strokes of luck and how the past is never forgotten.