It was supposed to be a romantic vacation for two: Finally, Magnus Bane, the charismatic warlock from Brooklyn, wanted to enjoy some intimate time with his great love, the Shadowhunter Alec Lightwood. But hardly had they arrived in Paris when they learned that a dark demon cult threatened to plunge the world into chaos. To put a stop to its mysterious leader, they embark on a dangerous hunt across Europe, where friend and foe are barely distinguishable. Magnus and Alec must trust each other blindly – but dark secrets put their relationship to a severe test.