The novel can be split into two different plots, or two different timelines: the present time with Evie as the main protagonist, and the past seen from Lady Agnes's journal. The plots are intertwined and at times it seems as though the past is repeating itself and the fates of the two girls are connected, even more complex than a simple blood relation.
Evie, Present
Evie has to move to a new place called Wyldcliffe, so she can attend the Abbey boarding school, because her father has to serve the military and her grandma is ill. On the way there the cab driver warns her of the rumors about the place, it's told to be haunted. As she makes her way to the school, she stumbles into a strange boy in a dark coat riding a horse. They awkwardly part and go on their ways, but Evie is left disturbed by the encounter. When she arrives at school, she is greeted by the Headmistress Mrs. Hartle who strictly tells her the rules, one of which is the ban of any jewelry such as the necklace around Evie's neck. The necklace was given to her by her grandma Frankie.
Evie has an awkward start at school, because she came late for supper and the other girls make fun of her ragged appearance, she didn't have time to change. The teacher tells her that she will be taking part in some tasks around the school, just like another girl who's there with a scholarship, like her. The girl's name is Helen, and she strikes Evie as strange and cold. Evie also becomes a target of bullying by another student called Celeste. Celeste blames her for taking the place of her late friend, who drowned in the nearby lake.
Trying to get accustomed to the new life Evie also starts having visions of a girl that is similar to her, but she brushes it off as a product of stress. She becomes friends with another girl at school called Sarah. She's been also sneaking out at night to meet with the boy she met the first night when she arrived at Wyldcliffe. His name is Sebastian and the more they see each other the closer they become and Evie starts falling in love with him. One night they go swimming in the lake and Evie suddenly gets a vision of a group of hooded people trying to pull her down. Scared and angry she tells Sebastian that they shouldn't see each other again.
Evie and Sarah have a conversation where Evie confesses to her about the visions she's been having and about the boy she's been seeing. Sarah tells her that she is a descendant of the Romany family and that she has visions of future and that she senses that Evie's in danger. The two girls spend the following week trying to discover more about the girl from Evie's visions, and they find out that she's Evie's ancestor and called Lady Agnes. They also discover a photo of a boy from Agnes's time that looks exactly like Sebastian and has the same name as well.
Evie decides to go ahead and confront Sebastian to tell her the truth, and he tells her that he is the same Sebastian from the past and that he found a way to outlive normal human life, but he's fading with time. He shows her Lady Agnes's journal that clears everything up for Evie, their relation and the visions she's been having. He is the one who unintentionally killed Agnes on the night she walked to her parents' home. In order to continue living Sebastian has to kill Evie and take Agnes's pendant containing her power from her. He tells her to disappear and never return again because he can't bear to hurt her.
Back at school, Evie and Sarah discover the truth about Helen. She is Mrs. Hartle's daughter and has special powers, she is a witch as well, just like Sarah and Mrs. Hartle is also a head of a coven disguised as school teachers that works for Sebastian in return for immortality. Helen decides to help Evie, to teach her to release the pendant's powers and become a witch just like Agnes. Evie feels Agnes's presence with her from that point, helping her as well.
There is a memorial held for Agnes and Celeste pranks the class by showing a makeshift of Agnes's ghost and makes it seem as though Evie was the one who did it. Evie has detention with Mrs. Hartle-in the meantime she discovered that detention is a disguise to drain the life force out of students to prolong Sebastian's life. She manages to escape Mrs. Hartle and ends up in a tomb, where she is cornered by the coven. They bring out Sebastian to hurt her, but he refuses to because he loves her. Helen and Sarah join Evie, and she finally releases her powers and together they manage to defeat the coven which disappears together with Sebastian. In the aftermath of those events Evie is determined to find Sebastian and find a way to save both of them without giving up on their love.
Lady Agnes's Journal
Lady Agnes's journal begins with her talking about her dear friend S. who came back from his travels to Morocco. He brought back a strange book with spells with him. The book promises great power to those who use it, and he convinces Agnes to start playing with the book together with him. Agnes casts a spell from the book that awakens her powers; the fire has spoken to her. In the aftermath of this extraordinary discovery Agnes starts seeing strange visions of a girl in that looks like her but strangely dressed.
Lady Agnes decides to use her powers to help others. She notices that Sebastian is in distress because he wasn't the one who gained the powers. He convinces her to cast a spell to give some powers to him. Sebastian discovers a part in the book that reveals how a male can become the leader of a coven that is willing to work for him and give him great powers, he's intrigued by this.
Agnes feels herself falling for Sebastian and is afraid of how far she will go to please him. Sebastian is growing more anxious by the day and his jealousy of Agnes is consuming him. One day he demands of her to make him immortal, she refuses, and he tells her that it makes her his enemy.
Agnes decides to run off to London and leave her old identity behind, because she's afraid of Sebastian and his demands. She desperately misses Sebastian and her old life and her only comfort is the girl she's been seeing in her visions, she realizes that it is her destiny to somehow help the girl. She casts a spell that puts all of her power into a pendant necklace, so that they are out of Sebastian's reach.
In the meantime, she married and has a little daughter, her husband passed away. She decides to return to Wyldcliffe for her daughter's future sake. At this point we discover that Evie's been reading the journal the entire time after Sebastian gave it to her and the rest of it is told in the present by Evie. Back at Wyldcliffe, Agnes is trying to find courage to go to her parents' home. One night she gathers the courage and sets on a walk there by herself.
