Four years have passed since the Dark War and the then twelve-year-old children- Emma Carstairs and Julian Blackthorn have been forced to grow up faster as both their parents were killed during the war. Julian and Emma are parabatai. A sacred bond between shadowhunters, forbidden to fall in love. Dead bodies start to turn up around the city bearing strange marks. They try to follow the leads and try to crack the mystery forming a potentially disastrous alliance with the fae.