Sixteen year old Cassandra Renfield has seen the mark since forever: a glow around certain people as if a candle were held behind their back.

The one time she mentioned it to someone else, the mark was dismissed as a trick of the light. So Cassie has kept quiet, considering its rare appearances odd, but insignificant. Until the day she watches a man die. Mining her memories, Cassie realizes she can see a person's imminent death. Not how or where, only when: today.

Cassie searches her past, her philosophy lessons, even her new boyfriend for answers, answers, always careful to hide her secret. How does the mark work? Why her?

Most importantly: if you know today is someone's last, should you tell them?