Lena (Alice Englert) learns that the only way to break the curse is if the person she loves dies. Unwilling to allow him to be hurt, and arguing that there are all kinds of ways someone you love can die, she erases Ethan's memories (Alden Ehrenreich) so that he completely forgets their time together.
The day of Lena's claiming comes. Ethan and Link are participating in a Civil War reenactment nearby. Link (Thomas Mann), who has been bewitched be Ridley (Emmy Rossum), shoots Ethan with a real bullet. Lena feels that something is wrong and rushes to the scene to find Ethan dying. Her mother Sarafine (Emma Thompson) and Ridley also appear and start goading her to strike out at the mortals and destroy them. Just as she starts to however, Ethan transforms into her uncle Macon (Jeremy Irons) who says he has paid the price and as someone she loved will die the curse will now be broken, he tells her not to listen to her mother but to 'claim herself' and then he dies. Lena confronts Sarafine but allows Ridley to beat a hasty exit. She causes the moon to vanish from the sky so she will not be claimed for either the light or the dark and then turns on her mother, forcing her out of the body of Mrs. Lincoln and (possibly?) kills her. Lena comes to the conclusion that a caster and a mortal can never be together.
Six months later, Ethan still does not remember. He is about to head off on a trip to visit some colleges. He runs into Lena and tells her that he regrets never getting to know her. Lena heads down in to the Caster's Library and we learn that she has become a half life half dark caster. Just as Ethan is about to drive out of town he spots the sign that Lena destroyed while they were making out, and he suddenly remembers everything. He gets out the car and screams her name. Down in the library, Lena looks up, as if she heard him, and the movie ends.