In the 1970s, a member of the IRA takes over an Active Service Unit in London after his wife is accidentally shot dead in Ireland. The unit’s mission is to cause chaos and destruction, while his personal aim is to hunt down his wife’s killer — an SAS captain, who is also hunting him.

Anna returns home after spending time in a psychiatric facility following her mother’s tragic death and discovers that her mother’s former nurse, Rachel, has moved into their house and become engaged to her father. Soon after she learns this shocking news, Anna is visited by her mother’s ghost, who warns her that Rachel has evil intentions.