1920, rural Ireland. Anglo Irish twins Rachel and Edward share a strange existence in their crumbling family estate. Each night, the property becomes the domain of a sinister presence (The Lodgers) which enforces three rules upon the twins: they must be in bed by midnight; they may not permit an outsider past the threshold; if one attempts to escape, the life of the other is placed in jeopardy. When troubled war veteran Sean returns to the nearby village, he is immediately drawn to the mysterious Rachel, who in turn begins to break the rules set out by The Lodgers. The consequences pull Rachel into a deadly confrontation with her brother - and with the curse that haunts them.

A chic, good-looking and suitably 70's couple arrive at an extravagant and deserted seaside hotel after eloping. Stefan is wealthy and happily English, with a hidden streak of sadism, while Valarie is intelligent but of inferior (Swedish) blood. To keep her with him at the eerie hotel he lies consistantly about his relationship with his mother and his plans to tell her of their marriage. Meanwhile he has mysterious phone conversations with an older, dominant and pampered sissy. Two fresh guests arrive; the Hungarian countess, Elizabeth Bathory and her voluptuous protege, Ilona. Virgin corpses begin showing up about the city drained of their blood. A wary detective lurks around the hotel taunting his only suspect, the Countess.

Lara (Eleanor Tomlinson) and her estranged father, Dr. Hill (Stephen Rea), travel behind the iron curtain to a decrepit castle outside the Hungarian town of Styria. In the nearby woods, Lara witnesses a violent car crash. Carmilla, (Julia Pietrucha), the lone survivor, crawls from the wreckage. When Lara hides this beautiful and mysterious stranger in the castle, the two start an intense and chaotic friendship. As their relationship deepens, crops whither, farm animals die, and the young women of Styria begin to go mad. When local girls are found dead from apparent suicides, Lara wonders if Carmilla is to blame or is there a darker secret behind the mass hysteria destroying the town.