There is an archway in Camden that was not there yesterday, and will pretend it was never there tomorrow.

Step through it and the fog turns to violets and old pennies, the gaslight burns the wrong colour, and a raven in an undertaker's hat looks you up and down as though measuring you for a box. Beyond it lies Camden Curiosities - Madame Morticia's Marvelous Market - where poison is sold honestly in labelled bottles, the pies occasionally scream, the florist arranges funeral bouquets for people not yet dead, and the monsters, against every instinct a sensible person owns, keep the kindest company in London.

Clara Wicks comes through the arch drenched in blood, clutching a length of mourning-lace woven from a murdered friend's hair. She wants one thing: the tradesman who turns poor girls into luxury grief-wear, brought to account. But the market deals only in true things, and the price of sanctuary is a single honest answer Clara is not yet willing to give.

Above the arch, a gentle, smiling reverend has begun to cleanse the city of its grief, its ugliness, and its inconvenient dead - with a white light that erases people as an act of love. He is coming for the market. And he is, all unknowing, already dressed in its victims.

To stop him, Clara will not have to become good. She will have to become honest - about her dead, about her rage, and about the hunger she shares with the very monsters she came to condemn.

The market laughs at death. It never laughs at suffering.

And it is very much open for business.