Already famous throughout Europe for his theories of planetary motion and gravity, Isaac Newton decided to take on the job of running the Royal Mint. And there, Newton became drawn into a battle with William Chaloner, the most skilful of counterfeiters, a man who not only got away with faking His Majesty's coins (a crime that the law equated with treason), but was trying to take over the Mint itself. But Chaloner had no idea who he was taking on. Newton pursued his enemy with the cold, implacable logic that he brought to his scientific research. Set against the backdrop of early eighteenth-century London with its sewers running down the middle of the streets, its fetid rivers, its packed houses, smoke and fog, its industries and its great port, this dark tale of obsession and revenge transforms our image of Britain's greatest scientist.