Freelance reporter Darcy Farthing boards a luxury cruise ship for a trip to beautiful Australian seaports with family and friends, where a baffling murder mystery challenges her investigative skills. The crimes begin when a small-town Kansas woman traveling with a class reunion tour group is plagued by an attack of yellow crazy ants, a dangerous, invasive species, as well as an illness caused by mysterious foodborne bacteria and the odd cancellation of an onshore tour. The bizarre but relatively minor incidents escalate when the ants injure more passengers and crew members. Soon, a peculiar death on the streets of Adelaide and attempted murders on board the ship threaten to cause panic. It is obvious that a crew member or passenger is targeting individuals, but who is it and why?
Meanwhile, Darcy is distracted by daughter Rachael’s uncharacteristic behavior and intense friendship with a handsome passenger. Reluctant to make waves, Darcy tries to suppress her concerns. She turns her full attention to the crimes when evidence is found in her friend and ex-husband Brooks’s stateroom and the security chief names him as the sole suspect. Brooks is clearly innocent, but the chief is inexplicably reluctant to conduct a more thorough investigation to clear him; then Darcy’s best friend, Sid, who is also Brooks’s fiance becomes the latest victim. Clue by clue, with husband Micks help, Darcy uses her skills to reveal a homicidal master of disguise and world-class computer hacker intent on exacting revenge related to a twenty-year-old crime.