DS Lucas Walker is off duty. His young half-sister Grace is visiting from Boston, and he’s supposed to be spending time with her at his home in Caloodie in outback Queensland. But instead they’ve driven 400 kilometres west to the tiny mining town of Kanpara to pick up Walker’s cousin Blair, who’s been digging for boulder opals and is suddenly very keen to get out. It’s not like Blair to quit so easily. Walker has the definite sense that something is off.

On their arrival, the atmosphere is already tense with rumours of a life-changing opal discovery. The following day, they awake to find that Kanpara has been completely cut off by a flood and the roads will be closed for days. As they take in their predicament, Blair receives a shocking phone call.

A man and a woman have been found brutally murdered.

The murdered woman’s husband is an immediate suspect, but Walker isn’t convinced. Could the killings be connected to the rumoured opal find? When the police take Blair in for questioning, the stakes couldn’t be higher for Walker. He must now work with his fellow officers to uncover the killer in the community’s midst before the waters recede and make escape possible. Can he unravel the mystery quickly enough to save his cousin and keep Grace safe?