Thomas's problems are more serious than those of a typical young Victorian gentleman. His elder brother may be sabotaging the family's bank. His childhood friend has died under mysterious circumstances. Far worse, leaves are sprouting on Thomas's skin. Perhaps it is all the fault of the long-rumored "Peculiarities" lurking in London's grey fog?

Proper society scoffs at the notion of magic, even as it seeps into their buildings, transfiguring the rich and poor alike. If Thomas is going to save the family business--and stop turning into a tree--he'll need help from some rather improper companions. Desperate for counsel, he seeks the advice of a lycanthropic medium and London's unacceptable occult society, including a strange fellow named Aleister Crowley.