Tamsin is the most powerful witch of her generation, but after committing the worst magical sin she is exiled by the ruling Coven and cursed with the inability to love. She can only get those feelings back-- temporarily-- by stealing love from others. Wren is a source, a person full of magic despite being unable to use it herself. As the only caretaker to her ailing father, Wren has spent her life hiding her secret. When her father falls victim to a magical plague that ravages the queendom, Wren proposes a bargain: if Tamsin will help her catch the dark witch responsible for creating the plague, then Wren will give Tamsin her love for her father.