When the 19-year-old daughter of a UK politician is found dead in Sydney Harbour, cultures clash as a British and an Australian detective team up to solve a complex murder mystery. But this international investigation will expose more than murder, as the two detectives begin to uncover a conspiracy with political consequences.

After her husband's abrupt death, Alice seeks solace with his remaining family — descendants of a leading researcher on demonic possession. As her in-laws transform one by one into creatures that feed on fear, she comes to discover that the vows she took in life survive even in death.