Fallen revolves around Luce, a young girl who is sent to Sword & Cross, a reform school, after accused of murdering a boy by starting a fire, but she cannot remember what happened exactly.
At the school, she meets Daniel, a handsome boy whom she feels attraction for him, and believes she had met him before. At the beginning, he feigns desinterest in Luce, traying to ignore her for her own safety. But after, Daniel explains everything to her, in other words, that the majority of people at the school are fallen angels, including him , and Luce has actually been Daniel's lover in past lives but they are both cursed and every time learns of her past and gets close to being with Daniel, she dies.
However, these fallen angels are on the side of God or are under Satan's rule, as Cam, who is the antagonist of the story and Luce's other romantic interest. He is continuously traying to seduce her, mainly wants making fun of Daniel. Despite she falls in love with him, at the and, she realizes her love for Daniel is very powerful and strong, whereas she has loved him for thousands of years.