1665, and the capital is awash with rumours of conspiracy. Thomas Chaloner knows that there are few grains of truth in the rumour-mill, but the loss of an important warship and the murder of Paul Ferine, a Groom of the Robes, makes him scent a whiff of genuine treason. As well as investigating the murder, Chaloner is charged with tracking down the leaders of a fanatical sect known as the Fifth Monarchists. Then, as he comes to know more about the Fifth Monarchists and their meetings on High Holborn, he discovers a number of connections - both to Ferine's murder and those involved with the defence of the realm. Connections that he must disentangle before it is too late to save the country...
