When a petty thief falls through a glass roof trying to escape the police what should have been the death of him marks the beginning of a whole new life.

For he is chosen as a medical guinea pig for the Scientific Society, where he comes into some very interesting information - a map of Sir Joseph Bazalgette's new sewage system.

Memorising the system and adopting the affectations of the rich young gentlemen of the Society, the thief uses his knowledge to become the most elusive burglar in Victorian London.

From now on, he will have two identities: Scarper - servant and sewer-rat, robbing jewels and making his escape by the underground labyrinth that lies beneath London - and Montmorency - fashionable, wealthy gentleman.

But Montmorency's new existence is fraught with danger - can he pull off the transformation and keep his secret safe...?