What if Celine was not Stephen Herondale's wife and Jace's mother, but Cassandra "Cassie" Branwell, who had to raise her son alone after the death of her husband, who died at the hands of Valentine. 20 years later, Valentine Morgenstern's daughter appears in the world of shadows, causing chaos, and to make matters worse, the biggest monster turns out to be alive. While searching for Clary mother, Cassie begins to have an secret affair with Magnus Bane, which will change her life.