THE RATS ARE COMING! THE WEREWOLVES ARE HERE!

In 1899, lives the eccentric Mooney family who reside in a large house in rural England. The invalid patriarch 'Pa' Mooney is a retired medical doctor who claims to be 180 years old. His eldest daughter, Phoebe, more or less cares for him and is head of the household. His eldest son, Mortimer, is a businessman who conducts the finances and contributes to the income. Younger daughter Monica is a sadist who keeps live rats as pets and frequently mutilates them and other small animals. Youngest son Malcolm is a halfwit with animalistic tendencies; the family keeps him locked in a room with live chickens. The family has a secret: they are all natural born werewolves who transform once a month on the night of the full moon. Pa Mooney has been researching for years to find a way to break the family curse.

Youngest daughter Diana returns home from medical school in Scotland with a new husband, a former classmate named Gerald, of whom Pa heartily disapproves. Pa tells Diana that she is the last hope the family has to overcome the ancient curse, since she is the only member of the family who does not turn into a werewolf on the night of the full moon. Will Diana succeed? Diana is eventually revealed to have other plans, and on top of that, she has her own secret as to why she is "different" from the other werewolves of the Mooney family.

Diana, the only family member immune to the werewolf curse, is revealed to have her own secret, complicating efforts to break the curse and resolve the family's fate.

The film’s conclusion pivots on Diana’s unique status within the family—her immunity to the curse isn’t the salvation the Mooneys hoped for, as her own motives and secrets emerge. The ending underscores the futility of escaping inherited monstrosity, with the family's internal tensions and hidden agendas ultimately thwarting any hope for redemption or normalcy.