The finger is pointing

One of the best historical detectives and at the same time historical novels of the twentieth century. The book, which is rightfully considered the classic of two genres at once.
This story happened in a stormy and dangerous era of the beginning of the restoration of Charles II. The story of betrayal, murder and some mysterious encrypted letter, which would be better to remain lost, because it can bring a very, very many on the block.
History, four versions of which will be told by four different participants in the events. But which of them is telling the truth, who is lying, who is silent about something, and who does not know the truth? A kind -hearted and frivolous Venetian, not too understanding the meaning of what is happening in a foreign country? A fanatically believer young man-Puritan, ready for anything to remove the charges of betrayal from his father? One of the best secret agents of Cromwell, now starting his own dangerous game? Or a thoughtful historian, for his misfortune, who loved the unsuitable girl?