Unforgiven wasn't at times an easy read, based as it is around themes of historical child abuse and organised paedophile rings. However, Sarah Barrie has undeniably created an unflinchingly gritty and compulsively readable crime-thriller. Readers who, like myself, don't mind some darkness and confronting themes in their crime fiction, will find Unforgiven difficult to put down once started.

The style of Unforgiven is quite distinct from earlier works of hers that I've previously read, which sit in the romantic-thriller subgenre (the Calico Mountain trilogy).

The story opens with Lexi Winter, a tough loner who struggles with alcohol abuse and other risk-taking behaviours as she tries to reconcile herself with her horrific past. On this particular morning, Lexi has a more immediate issue - the body of a man named Jonathan Davies is outside her Central Coast (NSW) unit, in the boot of her car...

As the narrative unfolds, we learn more about Lexi's disjointed life as an occasional sex worker and her personal crusade hunting child sex predators online.

Meanwhile, Detective Inspector Rachael Langley maintains a demanding career as a member of the State Crime Command's Homicide Unit. Despite her significant professional achievements over the years, notably in bringing notorious serial child murderer Thomas "The Spider" Biddle to justice, she remains haunted by her role in a child abuse case early in her career. When she receives a frightening phone call while enjoying a romantic dinner with her partner, Homicide Commander Superintendent Ed O'Hanlon, Rachael's attention is immediately drawn back to the investigation that defined her career. The stakes are raised when a child is found murdered in Gosford, the body staged in a way that seems to mirror the crimes of Thomas Biddle twenty years previously.

As Rachael's team heads to Gosford to investigate, Lexi comes to rely on the unlikely assistance of her neighbour Dawny in dealing with the little problem in her car boot. This storyline gives rise to many welcome moments of black humour as Lexi scrambles to stay barely one step ahead of authorities investigating Davies' disappearance.

The parallel storylines converge as our two very different heroines join forces to identify a cunning killer and desperately strive to prevent more children falling victim to a vicious web of paedophiles active on the Central Coast.

Sarah Barrie's plotting is well-paced and complex, without ever becoming convoluted, maintaining the reader's interest in both parallel storylines and skilfully using foreshadowing and the drip-feeding of historical details to maintain suspense. Both female main characters are well-conceived and convincing, the attitudes and behaviour of the highly intelligent but damaged Lexi providing an intriguing foil to Rachael's more orthodox police perspective.

Unforgiven raises some confronting moral questions about seeking vengeance for past wrongs, vigilante justice and the grey areas in the criminal justice system. However, it's hard not to cheer for a character who leverages her own appalling past experiences into a quest for moral (if not strictly legal) justice on behalf of others.

I found Unforgiven compulsively readable, despite its dark subject matter, and look forward to reading Sarah Barrie's future work in the competitive Aussie Noir genre - she's up there with the best! Substantial trigger warnings notwithstanding, I'd wholeheartedly recommend Unforgiven to any reader who loves gritty crime fiction in a contemporary setting. Readers who enjoy Candice Fox, Val McDermid and Stuart MacBride will gobble this one up - and those are not associations I bestow lightly!