1549. Freed from the galleys, the Scottish Reformer John Knox continues his mission as God's messenger to strike at the roots of papistry. A prophet without honor in his own land, he is welcomed as a chaplain by Edward VI in England. But by challenging the liturgy of the English Protestant Church, he makes dangerous enemies, and with Edward's untimely death and the accession of the Catholic Mary Tudor, Knox is forced to flee persecution. Despite the ever-present peril of capture, Knox crisscrosses Europe to ask the leading Reformation scholars his burning question - whether it is lawful to depose an ungodly monarch. While no answer is forthcoming, his plea has not gone unheeded. Someone is willing to commit regicide in his name. When Protestant Elizabeth I succeeds to the throne, Knox hopes to return with his young wife and family and resume his mission in England. However, while the charismatic preacher may have attracted a flock of female admirers, his polemical tract, The First Blast of the Trumpet against the Monstrous Regiment of Women, has antagonized Queen Elizabeth. Will Knox find a welcome in Scotland where the Lords of the Congregation are plotting revolution in the name of religion? Where his godmother, Elisabeth Hepburn, and Mary of Guise, are striving to stem the rising tide of reform and keep the throne for Mary Queen of Scots? And will the secret assassin achieve his aim?