Will Herondale and Jem Carstairs have a lot to contend with on a day to day basis: demons, curses, illness. With a huge drugs scandal affecting the mundanes of Victorian London that seems to have originated in the Shadow World, the last thing the duo need is any more problems. However, that's exactly what they get; in the form of unusual strangers Ciel Phantomhive and his peculiar butler Sebastian. However, as the Queen's guard dog, Ciel is also attending to an uncannily similar problem as the shadowhunters.

Who could be behind a problem that intertwines both worlds so closely?

Could the two sides of reality team up to help one another and save the world they share? Or will the Clave be correct, shadowhunters and mundanes just weren't made to work together?

Based on Yana Toboso's manga/anime Black Butler (Kuroshitsuji) and Cassandra Clare's The Infernal Devices novel series.