Neptune King down under is the 8th book in the Neptune King series. Shark is now engaged to Rebecca Evans and life looks pretty good, until he gets a call from his distraught younger sister Suzy. His mother has been savagely beaten by their drunken father and is now in hospital undergoing surgery for severe injuries, but that's not all. While at the hospital, their father is brutally murdered at the garage where he works and they no sooner come home than Dolphin (Shark's younger brother) is arrested for the murder of their father. Despite having a price on his head put on by the notorious biker gang, the Banderos, Shark drops everything to rush home to Australia intending to solve his father's murder and free Dolph. Neptune wants to come with him, but this is one thing Shark wants to do on his own. Once in Australia, Shark commences his investigation not realizing that his questions are causing panic amongst the guilty. He re-enacts his father's murder and realizes that there is far more behind it than mere domestic violence. Of course Dolph's case isn't helped when it turns out he's been lying to his lawyer and was seen in the vicinity of the garage on the night his father was killed, making Shark's job harder. Shark is relieved when his elder brother Lance returns from England to help him with the case. That relief is short lived as Lance is shot in a case of mistaken identity by the bikers. In learning this Neptune and Rachel pack their bags and head for Australia. As the evidence continues to pile up against Dolph, Shark concentrates on his only clue and just as he and Neptune make a breakthrough connecting the murder to organized crime, they are kidnapped by the bikers. Death is inevitable until Rachel buys into it with a little detective work of her own and the help of Shark's sister Suzie and Vessa Kelly who ran away from home in England to come be with Dolph. Escaping from the bikers, they go into hiding while continuing to work on the case. When their one and only suspect is also murdered, things look rather bleak until they encounter the head of the bikers, also in hiding as his boss, the head of the syndicate wants him dead as well in an effort to clean up loose ends. It's happy ending for the Johnson clan, but not so happy for Neptune.