In the autumn of 1829, the body of a wealthy young man is found dumped in a dust-pit behind one of London's most exciting new venues. Constable Sam Plank's enquiries lead him from horse auctions to houses of correction, and from the rarefied atmosphere of the Bank of England to the German-speaking streets of Whitechapel. And when he comes face to face with an old foe, he finds himself considering shocking compromises...

The new and highly organised Metropolitan Police are taking to the streets, calling into question the future of the magistrates' constables. Sam's junior constable, William Wilson, is keen, but what is an old campaigner like Sam to do when faced with the new force and its little black book of instructions?