Ranger Cal Nyx works alone in the vast NSW bush reserves but is pulled away from the quiet and solitude by a coded message that only one other person could understand. Dif, the only remaining link to her family, is in danger. He's also the last person the police are going to take seriously. No stranger to the complications of Dif's life, and with her femme MIA interstate, Cal burns rubber up and down a lonely coastline, calling in favours from her unique contacts to intercept a relentless killer. Are Cal's skills, badass bravado and risky schemes enough to bring a single-minded murderer out of the shadows? Can she save the one and only person who truly gets her?