Rena and Tom have been planning this trip for years: just the two of them, retired, setting out into remote bush country to enjoy nature's dramatic beauty --- and each other's company. When Tom dies unexpectedly just before they are to depart, Rena almost cancels, but there's nothing left at home but painful memories. She hits the road in her kitted-out truck. Not far from her first planned stop, Rena notices a fire burning some distance off the highway. Being a good citizen, she ventures off road, and is horrified to find a vehicle consumed by flames, with what's left of the driver still inside. When she learns that the victim is a fellow geologist, Rena begins an unofficial and unwelcome investigation fraught with deceit, diamond theft and murder. Had her old colleague found a new pipeline for the rare and valuable pink diamond, and been killed for it? And if Rena doesn't mind her own business, will she be next?

Mia's grief counseling practice, The Pleiades, is named for the seven sisters from Greek mythology who were the companions of the Goddess of the Hunt --- and who, in some stories, die of grief or are killed to be saved from attackers. Mia has been gathering broken women together for a radical form of group therapy --- five women crippled with grief by the murders of their sisters and seething with rage that the partners who killed them all walk free. She just needs one more. When Mia meets Naomi, she knows she has found the perfect candidate, but Naomi is resistant. She only needs to meet the others before she realizes that they, too, are consumed with desire for hands-on revenge. Under Mia's guidance, the women devise a plan to heal themselves. The premise is satisfyingly simple: I'll kill yours if you kill mine.