DS Lucas Walker is on leave in his hometown, Caloodie, taking care of his dying grandmother. When two young German backpackers, Berndt and Rita, vanish from the area, he finds himself unofficially on the case. But why all the interest from the Federal Police when they have probably just ditched the heat and dust of the outback for the coast? Working in the organised crime unit has opened Walker's eyes to the growing drug trade in Australia's remote interior - and he becomes convinced there is more at play. As the number of days since the couple's disappearance climbs, Walker is joined by Rita's older sister. A detective herself with Berlin CID, she has flown to Australia - desperate to find her sister. Their search becomes ever more urgent as temperatures soar. Even if Walker does find the young couple, will it be too late?