Constable Simon Pearce doesn't believe in love. It's a dangerous proposition for many people in 19th century London, but for an ambitious copper climbing Scotland Yard's greasy career ladder, it's out of the question.

He doesn't believe in monsters, either, though there seem to be a lot of them about. Whether it's a ghost haunting a London churchyard where men seek men's companionship, a phantom hound in Edinburgh that's hell-bent on revenge, or a murdered businessman on a cross-country train who just won't stay dead ― the mysterious has a way of finding Pearce, whether he wants it to or not.

But are these happenings truly supernatural? Or is something worse ― something thoroughly human ― to blame?

Pearce has his theories ― about crime, about monsters, and about love. But life has a way of testing even the most carefully considered ideas. And as he chases mysteries from one end of Britain to the other, he may just have to reconsider his ideas about all three.