This is an automatically translated description

All Magnus Bane has ever dreamed of is a holiday: a luxurious trip across Europe with Alec Lightwood, a shadowy hunter who, despite all the odds, ends up becoming his boyfriend.

But as soon as the lovers settle down in Paris, an old friend visits them and tells them about a demonic cult called the Crimson Hand that is wreaking havoc around the world.

Now Magnus and Alec must travel across Europe, tracking down the Crimson Hand and its elusive leader before the fanatics and the demons they summon do more damage. They must trust each other like never before - even if they have to uncover secrets they'd rather keep buried in the past.