Dublin 1817. Erin Galbraith, a girl who dreams of independence, lives in a world of men. She is unexpectedly forced to make a pact with a banshee, a supernatural creature who appears in houses, crying and keening, to announce the imminent death of one of those living there. The fact is that if Erin wants to save the life of her little brother, she must become the banshee's apprentice. "One life for another," says the Parca. The young Dublin girl has to go through a trial period of a year, and if after that time she has not managed to close her heart to any form of love, she will have failed and will die. Erin travels to the Scottish island of Skye, where she meets Declan O'Connor, an arrogant Highlander who, like her, has a great many secrets.