As Clary uncovers more about her family's past, she finds an ally in mysterious Shadow-hunter Sebastian. With Valentine mustering the full force of his power to destroy all Shadow-hunters forever, their only chance to defeat him is to fight alongside their eternal enemies. But can Downworlders and Shadowhunters put aside their hatred to work together? While Jace realizes exactly how much he's willing to risk for Clary, can she harness her newfound powers to help save the Glass City -- whatever the cost?
Love is a mortal sin and the secrets of the past prove deadly as Clary and Jace face down Valentine in the final installment of the New York Times bestselling trilogy The Mortal Instruments.