In present day, lonely sixteen-year-old Eleanor "Ella" Webb (Saoirse Ronan) and her sexy and protective mother Clara (Gemma Arterton) have been vampires for two hundred years. When a dangerous stranger hunts Clara down, she kills him, burns her apartment, and flees with Ella to a coastal town. Clara meets the lonely Noel (Daniel Mays), who is grieving the loss of his mother and is completely broken. He lodges them in his derelict Byzantium, a former hotel and bed-and-breakfast that belonged to his mother. Clara sees the chance to make money with a brothel for Noel and for her. Eleanor befriends teenager Frank (Caleb Landry Jones), who has leukemia, and they fall in love with each other. Meanwhile, two strangers are tracking Clara through the deaths of their victims. Eleanor is tired of living on the run and decides to tell their secret to Frank, but there are parts in Clara's past that she does not know.