While Nikki and Jack investigate the death of a man found on the site a rural building project, Leo is tasked with helping a grieving father’s discover the cause of his son’s fatal tumour. While Nikki is wooed by a charismatic junior Science Minister, Leo’s discovery of a similar medical condition in the man found dead on the building site reveals an abnormal cluster of tumour deaths, and a possible government cover up of their cause. When Leo suspects Nikki’s charming new man could be involved, it threatens their friendship, and leaves Leo and Jack battling to expose the sinister truth, and to discover just who is responsible for murder.