Emmaline Black has a secret. She can hear the rhythm of heartbeats. Not just her own, but others' too. It's a rhythm she's learned to control, and that can only mean one thing-- Emma's a witch. In a world where a sentence of witchcraft comes with dire consequences and all children who have reached the age of thirteen are tested to ensure they have no witch blood, Emma must attempt to stamp out her power before her own test comes. But the more she researches, the more she begins to suspect that her radically anti-witch aunt and mother are hiding something.