edward i, 1272-1307

In London, 1304, the Chief Justice Evesham who was accused of bribery and corruption is murdered and it may be Mysterium, a cunning killer, so Sir Hugh Corbett is ordered to investigate the murder.

Hugh Corbett, devoted emissary of King Edward I, is sent to Mistleham in January of 1304 in an effort to restore order after Scrope, an unscrupulous manor lord, goes back on his promise to return a priceless cross he stole from the Templars during the Crusades, and murders as heretics fourteen members of a religious order, but Corbett arrives to find the situation has deteriorated with the arrival of a mysterious bowman who is killing people at random.

Sir Hugh Corbett, Keeper of the Secret Seal of Edward I of England, organizes agents in Paris to steal the book of secrets written in code by monk and scholar Roger Bacon, resulting in a meeting between the scholars of England and France who come together at Corfe Castle in an effort to break the code, only to encounter murder and mayhem.