The war is over, and Clary Fray is excited to return to New York, where a new world full of possibilities awaits her. He trains diligently to become a Shadowhunter and use his special abilities. Her mother is marrying the love of her life. Shadowhunters and Underworlders finally live in peace with each other. And most importantly, Clary and Jace's love can finally come true.

However, someone starts killing Shadowhunters, and the rising tension threatens another bloody war. Clary's best friend Simon can't help either. Everywhere you turn, someone wants to side with you, because they need the terrible power of the curse that is ruining your life. Not to mention that he is dating two beautiful but dangerous girls at the same time, neither of whom knows about the other.

When Jace begins to distance himself from Clary without explanation, she finds herself in the middle of a mystery whose solution will make her worst nightmare come true. It sets off a chain of terrible events that may even end up in him losing everything that is important to him. Even Jace.