Haunted by a strange, ghostly experience from her youth and lonely in her isolated castle, Laura longs for a companion. Suddenly, her wishes are answered.

Through a curious series of events, a beautiful young stranger named Carmilla becomes a ward at Laura's family home. The girl is odd, but friendly, and Laura welcomes her with open arms. However, Carmilla is hiding a dark secret--one that could cost Laura everything.

All around them, paranoia and fear sweep the countryside as villagers fall victim to a mysterious illness. Plagued by fever, declining health, and horrifying visions, Laura soon realizes that the villagers' symptoms match her own. Somehow Carmilla is at fault, but the truth is more sinister than Laura ever could have imagined.