A small mining town. A brutal double murder. A killer among them.

DS Lucas Walker is off duty. He's supposed to be showing his little sister Grace the Australian outback, on her visit from Boston, but instead they're headed out bush- where Walker's cousin has been mining for boulder opal. Something seemed off when Walker heard that Blair wanted to get out of Kanpara, so he and Grace are en route to bring him home to Caloodie.

But Kanpara is in Channel Country, and a major flood is on the way.

The atmosphere in the isolated mining town is already tense with rumours of a big opal find, and whenWalker, Grace and Blair wake up the next day they find themselves completely cut off. A deluge far north has run off into the rivers that make up this unique ecosystem, and the roads will be impassable for days. As they take in their predicament, Blair receives a shocking phone call.

Two bodies have been found, brutally murdered.

The husband is an immediate suspect, but Walker is not convinced. And when Blair is taken in for questioning, the stakes couldn't be higher. Before the water recedes, he must work with local police to uncover the killer in their midst. Can Walker act fast enough to save his cousin, and keep Grace safe?

The third thrilling instalment in the gripping and bestselling DS Lucas Walker series is full of breathtaking twists and dark turns - for fans of Jane Harper, Cara Hunter and Chris Whitaker.